In e na ional Jou nal o Human Resea ch and Social Science S udies
ISSN(p): 3050-547X, ISSN(e): 3050-5488
Volume 02 Issue 11 No embe , 2025
DOI: h ps://doi.o g/10.55677/ijh sss/16-2025-Vol02I11
Page No : 892-905
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Resonan B ea hwo k as Mul imodal Vagal–In e ocep i e Modula ion: An
Empi ical Syn hesis o Non-in asi e VNS, B ea hing-D i en In e ocep ion
and Respi a o y Tools
Pipe Hu son1, James Hu son2
1,2Lindenwood Uni e si y, USA
1h ps://o cid.o g/0000-0002-1787-6143, 2h ps://o cid.o g/0000-0002-0578-6052
ABSTRACT: Resonan B ea hwo k is p oposed as a laye ed, measu able in e en ion ha
modula es agal ac i i y and in e ocep i e p ocessing h ough acous ic ocaliza ion, espi a o y
mechanics, and bio eedback. This e iew syn hesizes human empi ical s udies om 2022–2025
ac oss i e domains: (1) nonin asi e anscu aneous au icula agus ne e s imula ion and
acous ic o ocal agal engagemen ; (2) in e ocep ion a ge s modula ed by b ea hing; (3)
espi a o y ehabili a ion ools, including oscilla o y posi i e expi a o y p essu e and inspi a o y
muscle aining; (4) i ual o augmen ed eali y b ea h bio eedback; and (5) neu oimaging o
high en ila ion b ea hwo k wi h music. E idence shows aVNS can acu ely inc ease agal
indices, wi h e ec s con ingen on equency and pulse wid h, while paced humming o singing
nea 0.1 Hz enhances espi a o y sinus a hy hmia and posi i e a ec . B ea hing phase shapes
pe cep ion and neu al exci abili y; exhala ion weigh ing and slow pacing ampli y hea bea
e oked po en ials and a en ion o in e nal signals. OPEP imp o es ai way clea ance and
symp oms, and inspi a o y aining inc eases inspi a o y s eng h wi h shi s owa d
pa asympa he ic balance, sugges ing au onomic co bene i s beyond pulmona y gains. XR
deli e y yields physiologic ou comes compa able o non XR bio eedback bu imp o es
engagemen and ans e in s ess laden con ex s. Neu oimaging du ing high en ila ion plus
music e eals educed pe usion in in e ocep i e co ex and inc eased pe usion in limbic egions
alongside sympa he ic ac i a ion and pos session emo ional elie . Findings align wi h a es able
amewo k in which acous ic esonance, mechanical load, and eedback guided iming join ly
modula e agal e e ence and in e ocep i e ci cui y, wi h ansla ional po en ial o
neu odi e gen and pos i al dysau onomia.
Co esponding Au ho :
Pipe Hu son
KEYWORDS:
Resonan b ea hwo k,
T anscu aneous au icula
agus ne e s imula ion,
In e ocep ion, Hea a e
a iabili y, Oscilla o y
posi i e expi a o y p essu e
I. INTRODUCTION
Resonan B ea hwo k deno es a h ee-laye cons uc ha in eg a es (a) ocal–acous ic agal engagemen h ough humming, oning,
o paced singing; (b) mechanical oscilla ion and esis ance ia oscilla o y posi i e expi a o y p essu e and inspi a o y loading; and
(c) bio eedback-suppo ed pacing ha s abilizes espi a o y hy hm and ca dio espi a o y coupling. Acous ic engagemen nea he
esonance equency (~0.1 Hz) yields espi a o y sinus a hy hmia ampli ica ion compa able o paced b ea hing, indica ing a
p ac icable ou e o agal modula ion h ough oice p oduc ion and sound-media ed exhala ion con ol (Tanzmeis e e al., 2022).
Mechanical aids, including OPEP de ices and inspi a o y muscle aining, p o ide quan i iable gains in ai way clea ance, pe cei ed
b ea hlessness, and inspi a o y s eng h, wi h eme ging e idence o au onomic co-bene i s e lec ed in hea - a e a iabili y shi s
(Alghamdi e al., 2023; Sa-nguanmoo e al., 2025). Bio eedback-suppo ed pacing deli e ed h ough imme si e o con en ional
in e aces s anda dizes a e and dep h while sca olding adhe ence, al hough andomized e idence sugges s physiological e icacy
ha ma ches non-VR compa a o s a he han su passes hem (Co ez-Vázquez e al., 2024). Clinical ele ance is p onounced o
neu odi e gen and pos - i al coho s cha ac e ized by dysau onomia, b ea h i egula i y, and in e ocep i e dis up ion, whe e
inspi a o y aining and s uc u ed espi a o y p ac ice ha e demons a ed imp o emen s in b ea hlessness domains and unc ional
indices (McNa y e al., 2022). Con e gen neu omodula ion s udies addi ionally indica e ha anscu aneous au icula agus ne e
s imula ion ( aVNS) can acu ely inc ease pa asympa he ic indices—pa icula ly high- equency HRV—wi h age and pa ame e
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se ings mode a ing e ec size (Gianlo enço e al., 2024; Maes i e al., 2024). Ye pa ame e -sensi i i y ials e eal he e ogeneous
HRV esponses ac oss equency–pulse-wid h combina ions, unde sco ing he need o p o ocol op imiza ion (A anacko e al.,
2025). A he uppe a ousal bounda y o b ea h-based p ac ices, high- en ila ion b ea hwo k combined wi h music p oduces al e ed
s a es ma ked by dec eased HRV du ing induc ion and egionally speci ic pe usion shi s on ASL-MRI— indings ha complemen
slowe esonance egimens wi hin a uni ied con inuum o au onomic and a ec i e modula ion (Ka a e al., 2025).
Despi e hese ad ances, he e iden ia y landscape emains agmen ed ac oss aVNS ials, ocal pacing s udies, espi a o y de ices,
and XR bio eedback sys ems, which hinde s cumula i e heo y-building and pa ame e ized p o ocol design. The p esen a icle
add esses his gap by delimi ing i s scope o human empi ical wo k om 2022–2025 ha epo s physiological endpoin s capable
o indexing au onomic and in e ocep i e change: HRV (e.g., RMSSD, HF), espi a ion me ics ( a e, a iabili y, end- idal CO₂),
spi ome y and espi a o y muscle s eng h, EEG hea bea -e oked po en ials (HEP), and ASL-MRI o MRI pe usion. Fi e ocus
domains s uc u e he syn hesis: (1) non-in asi e VNS and acous ic/ ocal agal engagemen ; (2) in e ocep i e a ge s modula ed
by b ea hing; (3) espi a o y ehabili a ion ools wi h measu able physiology; (4) VR/AR and HCI b ea h bio eedback; and (5)
neu oimaging o high- en ila ion b ea hwo k wi h music. Mechanis ic in e ocep ion indings cons ain iming choices: exhala ion
phases enhance HEP ampli ude du ing hea bea a en ion, and espi a o y phase wo seconds be o e ac ion p edic s esponse speed
and accu acy, implying design le e age o exhale-weigh ed cues and ~0.1 Hz pacing (Zacca o e al., 2024; Ha ing e al., 2025).
Respi a o y ools p o ide obus pulmona y endpoin s and, whe e assessed, shi s in sympa ho agal balance ha align wi h educed
e o and imp o ed egula ion (Alghamdi e al., 2023; Sa-nguanmoo e al., 2025). Me a-analy ic e idence indica es ha VR
b ea hing in e en ions a e no in insically supe io o non-VR b ea hing on men al heal h, HR, o HRV ou comes, bu imme si e
deli e y may s ill augmen adhe ence and skill ans e in s ess ul con ex s o use (Co ez-Vázquez e al., 2024). Al oge he , hese
s eams mo i a e an in eg a ing amewo k ha links acous ic esonance, mechanical loading, and eedback-guided pacing o
ep oducible au onomic and in e ocep i e signa u es.
The cen al hypo hesis ad anced he e posi s ha laye ed acous ic–mechanical– eedback inpu s shi agal indices and in e ocep i e
me ics in p edic able, pa ame e -dependen ways ha can be enginee ed h ough selec ion o equency, pulse wid h, mon age,
pacing a e, and exhale/inhale weigh ing. Me hodologically, he e iew ollows PRISMA-aligned iden i ica ion, sc eening, and
ex ac ion, wi h isk-o -bias app aisal and anspa en e ec -di ec ion syn hesis ac oss he e ogeneous endpoin s (Page e al., 2021).
Pa ame e -sensi i i y mapping is unde aken o aVNS ( equency, pulse wid h, la e ali y) and o ocal/paced b ea hing nea
esonance, wi h a en ion o espi a ion con ol du ing HRV acquisi ion and o mon age-speci ic a e en engagemen . The analysis
c oss-walks measu emen amilies— ime- and equency-domain HRV, espi a ion me ics and capnog aphy, spi ome y and
MIP/MEP, EEG HEP, and ASL-MRI— o he h ee laye s o Resonan B ea hwo k o in o m dose, sequence, and sa e y moni o ing.
E idence p io i ized includes andomized o c osso e aVNS ials wi h au onomic eadou s, mechanis ic singing/humming
p o ocols, con olled s udies o OPEP and IMT, XR bio eedback ials o me a-analyses, and he ecen ASL-MRI b ea hwo k–
music in es iga ion (Gianlo enço e al., 2024; Maes i e al., 2024; A anacko e al., 2025; Tanzmeis e e al., 2022; Alghamdi e
al., 2023; Sa-nguanmoo e al., 2025; Co ez-Vázquez e al., 2024; Ka a e al., 2025). In ended con ibu ions include a pa ame e ized
p o ocol empla e, a me ics- o-design map aligned wi h s udy objec i es, and ansla ional ecommenda ions o neu odi e gen
and pos - i al use-cases whe e dysau onomia and in e ocep i e dys egula ion a e salien cons ain s. By in eg a ing acous ic,
mechanical, and eedback laye s unde a common measu emen a chi ec u e, he a icle u nishes a es able model o laye ed
b ea h– agus in e en ions and a oadmap o nex -gene a ion con olled ials (Figu e 1).
Figu e 1. Concep ual Sys ems Diag am o Resonan B ea hwo k
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II. LITERATURE REVIEW
A) Non-in asi e VNS and acous ics. Recen andomized and c osso e ials indica e ha aVNS can acu ely modula e au onomic
indices, wi h he e ogenei y d i en by s imula ion pa ame e s and sample cha ac e is ics. In a sham-con olled RCT, aVNS inc eased
high- equency HRV (HF) ela i e o sham, wi h age mode a ing he e ec such ha olde adul s exhibi ed la ge HF gains—
consis en wi h g ea e head oom o pa asympa he ic up- egula ion (Gianlo enço e al., 2024). Pa ame e -sensi i i y wo k using a
wi hin-subjec c osso e design demons a ed ha speci ic equency–pulse-wid h pai s (e.g., 10 Hz×250–500 µs; 25 Hz×100 µs)
can aise o e all a iabili y (SDNN) wi hou eliably changing RMSSD, unde sco ing a dis inc ion be ween global a iabili y and
agally media ed indices (A anacko e al., 2025). Con e ging e idence om a double-blind, sham-con olled exe cise s udy shows
ha one week o daily aVNS inc eased VO₂peak (~3–4%) and peak wo k a e while a enua ing in lamma o y esponses, sugges ing
ca dio espi a o y and immunomodula o y bene i s beyond es ing HRV (Ackland e al., 2025). No all ials show agal
enhancemen : a c osso e s udy epo ed dec eases in RMSSD and HF du ing aVNS wi hou hea - a e change, implying con ex -
o pa ame e -dependen a ousal e ec s o agal a e en ac i a ion (Kaduk e al., 2025). Mon age also ma e s; pos hoc compa isons
a o in-ea ( agus/concha) placemen s o e behind-ea si es o RMSSD inc eases, aligning wi h au icula agal inne a ion
densi y (Pe cin e al., 2024). Complemen ing elec ical s imula ion, acous ic/ ocal p o ocols nea he ca dio espi a o y esonance
equency (~0.1 Hz) p oduce obus RSA: paced singing a 0.1 Hz ma ched slow-b ea hing bene i s on HRV, wi h added posi i e
a ec (Tanzmeis e e al., 2022), and b ie humming o OM chan ing ele a ed HRV ime- and equency-domain ma ke s in ield
and lab assessmen s (T i edi e al., 2023; Inba aj e al., 2022). Taken oge he , hese indings posi ion acous ic p e-ac i a ion
(humming/ oning) as a low-ba ie en y o agal engagemen and in eg a ion-phase ocaliza ion (paced singing) as a means o
sus ain esonance wi hin he Resonan B ea hwo k sequence.
B) In e ocep ion modula ed by b ea hing. A g owing body o e idence cla i ies how espi a ion phase and b ea h- ocused
a en ion shape pe cep ion and b ain dynamics, wi h di ec implica ions o cue iming in p o ocols. A la ge mul i-da ase analysis
showed ha espi a o y phase ~2 s be o e esponse p edic s eac ion- ime and accu acy luc ua ions ac oss asks, implying a
sys ema ic, ime-lagged coupling be ween b ea hing and senso imo o eadiness (Ha ing e al., 2025). EEG wo k demons a es ha
exhala ion p e e en ially ampli ies he HEP and imp o es hea bea de ec ion accu acy du ing in e ocep i e a en ion, suppo ing
exhale-weigh ed asking when aining in e ocep i e p ecision (Zacca o e al., 2024). B ea h- ocused MRI pa adigms e eal a
cha ac e is ic neu al signa u e: widesp ead co ical deac i a ion wi h p ese ed o s eng hened ACC–do sal a en ion connec i i y
du ing b ea h awa eness, pa icula ly in indi iduals wi h highe in e ocep i e sensibili y (Fa b e al., 2023). These labo a o y
obse a ions cohe e wi h epo s ha oli ional slow b ea hing en ains del a– he a oscilla ions and modula es limbic–insula
ne wo ks, o e ing a mechanis ic subs a e o he a en ional quie ing and enhanced bodily signal gain a ge ed by esonance-paced
p ac ice (con ex ualized in he sou ces abo e). Dis inguishing in e ocep i e accu acy (objec i e pe o mance) om in e ocep i e
awa eness (subjec i e sensibili y) is he e o e c i ical; phase-speci ic p o ocols can be s uc u ed o a o accu acy gains (e.g.,
exhale-locked hea bea asks) while b ea h-awa eness blocks can consolida e a en ional s abili y e lec ed in la ge-scale ne wo k
dynamics. Collec i ely, hese s udies a gue o slow pacing (~0.1 Hz) wi h exhale-emphasis du ing in e ocep i e d ills inside
Resonan B ea hwo k, so ha cueing aligns wi h phases o maximal co ical ecep i i y o in e nal signals (Zacca o e al., 2024;
Ha ing e al., 2025).
C) Respi a o y ehabili a ion ools. Con olled ials since 2022 suppo oscilla o y posi i e expi a o y p essu e (OPEP) and
inspi a o y muscle aining (IMT) as mechanical le e s wi h measu able physiology ha may ca y au onomic co-bene i s. In he
O-COPD andomized ial (n = 122), h ee mon hs o Acapella OPEP imp o ed cough-speci ic quali y o li e, educed 24-h cough
coun s, and enhanced a igue and gene ic heal h indices e sus usual ca e, consis en wi h clinically meaning ul ai way-clea ance
gains (Alghamdi e al., 2023). In b onchiec asis, a 6-mon h single-a m pilo epo ed ewe exace ba ions and imp o ed
B onchiec asis Heal h Ques ionnai e sco es wi h wice-daily Flu e use, alongside ansien inc eases in spu um olume—an
expec ed ma ke o mobiliza ion (Kim e al., 2023). Rega ding au onomic ou comes, a 4-week RCT in obese young adul s ound
ha IMT (55% MIP) inc eased inspi a o y s eng h and shi ed sympa ho agal balance (LF/HF ↓) wi hou al e ing spi ome ic
olumes, sugges ing an HRV bene i a ibu able o espi a o y-muscle loading a he han pa enchymal change (Sa-nguanmoo e
al., 2025). Fo pos - i al eco e y, an RCT in long-COVID showed home-based IMT imp o ed b ea hlessness and espi a o y-
muscle unc ion—a clinical pla o m on which au onomic indices can be laye ed in u u e ials (McNa y e al., 2022). While HRV
endpoin s a e no ye ou ine in ai way-clea ance ials, he p olonged, esis i e exhala ion in insic o OPEP and he ba o e lex-
salien inspi a o y loading o IMT plausibly os e RSA and agal ebound when embedded wi hin esonance-paced sessions,
aligning hese de ices wi h he mechanical laye o Resonan B ea hwo k.
D) VR/AR and HCI b ea h bio eedback. The cu en RCT e idence indica es ha imme si e deli e y does no in insically
ou pe o m non-imme si e deli e y on physiologic egula ion, e en as i may enhance adhe ence o skill gene aliza ion in high-
a ousal con ex s. A 2024 sys ema ic e iew and me a-analysis o six RCTs ound no signi ican di e ences be ween VR and non-
VR b ea hing in e en ions on men al-heal h ou comes, hea a e, o HRV, no in use likeabili y o in ended u u e use (Co ez-
Vázquez e al., 2024). A he same ime, single-case and aining s udies sugges ha closed-loop bio eedback inside ecologically
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alid VR scena ios can s eng hen olun a y HRV con ol and b ea hing egula i y unde s ess—an e ec p o ile aluable o
ans e , e en i session-le el physiology ma ches non-VR p ac ice (Michela e al., 2022; Michela, 2024). B oade ehabili a ion
epo s in eg a ing VR wi h pulmona y p o ocols in pos -COVID popula ions show easibili y and unc ional gains, hough hey
a ely isola e b ea h-bio eedback’s unique con ibu ion o HRV endpoin s (Ru kowski e al., 2023). The esul ing pic u e is one o
pa i y in acu e physiological e ec s bu po en ial ad an ages in engagemen , dosage, and con ex -speci ic skill acquisi ion,
posi ioning XR as a deli e y ampli ie o he bio eedback-suppo ed pacing laye a he han a ca ego ical e icacy upg ade o e
con en ional ools (Co ez-Vázquez e al., 2024; Michela e al., 2022).
E) B ea hwo k plus music neu oimaging. High- en ila ion b ea hwo k (HVB) accompanied by e oca i e music e okes al e ed-
s a e phenomenology wi h a dis inc i e au onomic–neu al signa u e ha complemen s slowe esonance p ac ices. In a mul imodal
s udy spanning online, lab, and MRI coho s, ASL-MRI du ing sus ained HVB e ealed educed pe usion in le pos e io
insula/pa ie al ope culum (in e ocep i e/sel egions) and inc eased pe usion in igh amygdala–an e io hippocampus (emo ion–
memo y), wi h egional changes acking “oceanic boundlessness” (uni y/bliss) a ings; concu en ly, HRV dec eased du ing
induc ion, deno ing sympa he ic ac i a ion (Ka a e al., 2025). P ess summa ies om ins i u ional and science ou le s con e ge on
his pa e n—global CBF educ ions wi h ocal limbic inc eases, educed ea /nega i e a ec a e sessions, and no ad e se e en s—
unde sco ing a “ho me ic” s ess na a i e consis en wi h ca ha ic emo ional p ocessing (Neu oscience News, 2025; Uni e si y o
Sussex/BSMS, 2025). Concep ually, hese indings ex end he in eg a ion phase o Resonan B ea hwo k: while esonance-paced
ocaliza ion aims o agal/RSA cohe ence and a en ional quie ing, HVB-plus-music ansien ly upshi s a ousal o access limbic
ci cui s, wi h pos -session elie and posi i e a ec sugges ing complemen a y mechanisms along a single espi a o y-neu al
con inuum. Me hodologically, he HVB s udy ancho s me ic selec ion o al e ed-s a e a ian s (ASL-MRI CBF maps + HRV
ajec o ies) while he slow-b ea hing li e a u e ancho s RSA and in e ocep i e eadou s— oge he u nishing an empi ically
g ounded pale e o ou comes o laye ed, pa ame e ized b ea h p o ocols (Ka a e al., 2025; Tanzmeis e e al., 2022).
III. METHODOLOGY
The e iew adop ed a p io i eligibili y c i e ia ha con ined inclusion o human empi ical s udies published be ween Janua y 1,
2022 and Sep embe 17, 2025, each epo ing a leas one physiological endpoin pe inen o au onomic, espi a o y, o in e ocep i e
unc ion: HRV (RMSSD, HF powe , LF/HF, RSA), espi a ion me ics ( a e, a iabili y, end- idal CO₂), spi ome y (FEV₁, FVC),
espi a o y muscle s eng h (MIP/MEP), EEG hea bea -e oked po en ials (HEP), and ASL-MRI ce eb al blood low (CBF).
Ta ge ed popula ions included neu o ypical adul s, neu odi e gen coho s, and pos - i al g oups (e.g., long COVID), wi h heal hy-
adul mechanis ic expe imen s eligible when hey cla i ied pa hways o pa ame e s. S udy designs encompassed andomized and
c osso e ials, con olled coho s, p e egis e ed pilo s, and pee - e iewed sys ems/enginee ing pape s wi h human da a, while
excluding single-case epo s wi hou physiology, opinion pieces, and unblinded p og am e alua ions lacking objec i e endpoin s.
In o ma ion sou ces comp ised PubMed/PMC, JAMA Ne wo k, Wiley Online Lib a y, PLOS, eLi e, Sp inge Link, ScienceDi ec ,
bioRxi /medRxi ( o p e egis e ed pilo s), and ClinicalT ials.go ( o ongoing ials and p o ocol pa ame e s), wi h he sea ch and
epo ing amewo k aligned o PRISMA 2020 (Page e al., 2021). Sea ch s ings combined domain e ms (e.g., “ aVNS RMSSD,”
“humming 0.1 Hz HRV,” “OPEP Flu e FEV1,” “IMT MIP LF/HF,” “VR b ea hing HRV,” “ASL-MRI b ea hwo k CBF”) wi h
da e limi s and human il e s; o wa d–backwa d ci a ion chasing complemen ed da abase que ies. Because HRV is sensi i e o
espi a ion, inclusion a o ed s udies ha ei he con olled b ea hing o epo ed espi a o y a e/E CO₂ du ing HRV acquisi ion,
consis en wi h ecen guidance on hea - a e and espi a o y epo ing (Quigley e al., 2024; Damoun e al., 2024). Fo ASL-MRI
ou comes, da a abs ac ion ollowed con empo a y consensus on acquisi ion and epo ing (Lindne e al., 2023; Suzuki e al., 2024),
ecognizing he con inued ele ance o he ISMRM/ESMRMB whi e pape (Alsop e al., 2015). A p o ocol and codebook
enume a ing eligibili y decisions, a iable de ini ions, and planned analyses we e main ained o suppo anspa en eplica ion
unde PRISMA 2020 con en ions (Page e al., 2021).
Sc eening p oceeded ia dual- e iewe i le/abs ac checks ollowed by ull- ex con i ma ion, wi h disag eemen s esol ed by
consensus and eco ded in a PRISMA low diag am (Page e al., 2021). Da a ex ac ion cap u ed bibliog aphic de ails; popula ion
(diagnosis, age, sex), sampling and se ing; in e en ion pa ame e s— o aVNS: equency (Hz), pulse wid h (µs), du y cycle/on–
o scheduling, la e ali y/mon age ( agus, cymba conchae, ea lobe con ol), session leng h and dose; o acous ic/ ocal p o ocols:
pacing a e (b ea hs/min), exhale- o-inhale a io, phona ion ype (humming, OM, singing); o OPEP/IMT: de ice model,
esis ance/p essu e a ge s, session equency/du a ion; o XR bio eedback: de ice class, bio eedback a ge s, ask con ex ; and o
ASL-MRI: labeling scheme, PLD, eadou , backg ound supp ession, CBF quan i ica ion model. Compa a o s (sham, wai -lis , usual
ca e, non-VR analogues) and endpoin s (HRV domains, espi a o y me ics, spi ome y, MIP/MEP, EEG HEP, ASL-CBF), plus
adhe ence and usabili y indica o s (session coun s, comple ion a es, ad e se e en s, use a ings), we e sys ema ically eco ded.
Risk o bias was app aised using RoB 2 o andomized ials (S e ne e al., 2019), ROBINS-I o non- andomized s udies (S e ne
e al., 2016), and QUADAS-2 when diagnos ic/accu acy pa adigms we e ele an (Whi ing e al., 2011). To enhance in e p e abili y
ac oss he e ogeneous au onomic ou comes, ex ac ion also no ed whe he b ea hing was paced o spon aneous, whe he E CO₂ was
moni o ed, and whe he HRV was compu ed o e s able epochs—choices suppo ed by con empo a y epo ing ecommenda ions
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Page 896 o 905
(Quigley e al., 2024; Damoun e al., 2024). All ex ac ions we e double-en e ed wi h p og ammed checks o in e nal consis ency
(e.g., equency–pulse-wid h alignmen , mon age plausibili y, espi a o y pacing cohe ence), and disc epan en ies we e
adjudica ed agains he ull ex . A li ing log documen ed p o ocol de ia ions and a ionale, wi h ci a ions o he ele an
me hodological s anda ds (Page e al., 2021; Lindne e al., 2023; Suzuki e al., 2024).
Quan i a i e syn hesis ollowed a hie a chical plan ha p i ileged like-wi h-like compa isons and espec ed pa ame e iza ion.
Whe e ≥ 3 su icien ly homogeneous s udies epo ed a common me ic (e.g., RMSSD change unde aVNS s sham; MIP change
unde IMT s con ol; HF-HRV unde 0.1 Hz ocaliza ion s paced b ea hing), a andom-e ec s me a-analysis was unde aken wi h
he e ogenei y quan i ied (I²) and small-s udy bias explo ed pe majo handbook guidance (Higgins e al., 2023). When pooling was
in easible, esul s we e o ganized using an e ec -di ec ion hea map and summa ized unde SWiM epo ing p inciples, a oiding
signi icance-based o e coun ing and ins ead using di ec ion-o -e ec wi h app op ia e unce ain y whe e possible (Campbell e al.,
2020; Cumps on e al., 2022). Fo aVNS, a me a- eg ession p obed equency, pulse wid h, du y cycle, and mon age as mode a o s
o HRV esponses, and sensi i i y analyses e-es ima ed e ec s a e (a) excluding s udies wi hou b ea h con ol o E CO₂
moni o ing, (b) s a i ying by b ea hing a e ( esonance s non- esonance), and (c) s a i ying by mon age ( agus/cymba s ea lobe).
Fo ocal/acous ic s udies, sensi i i y assessed whe he phona ion (humming/OM s silen esonance b ea hing) o pacing (~0.1 Hz
s o he ) mode a ed RSA ou comes; o OPEP/IMT, analyses es ed whe he au onomic shi s (e.g., LF/HF dec ease) pe sis ed a e
adjus ing o pulmona y imp o emen s (MIP/FEV₁). Subg oup analyses mapped indings o neu odi e gen and pos - i al coho s
when epo ed, and a pa allel me ic- o- amewo k c oss-walk linked each endpoin amily o he acous ic, mechanical, and eedback
laye s o Resonan B ea hwo k, he eby in o ming pa ame e ized p o ocol design. Finally, obus ness checks emo ed high-bias
s udies (pe RoB 2/ROBINS-I domains), epea ed analyses wi h espi a ion-no malized HRV subse s, and iangula ed physiological
conclusions ac oss modali ies (HRV– espi a ion–spi ome y–HEP–ASL), aligning in e p e i e claims wi h he weigh and quali y
o e idence (S e ne e al., 2019; S e ne e al., 2016; Campbell e al., 2020) (Table 1).
Table 1. Ou come Me ics C oss-Walk o Resonan B ea hwo k Laye s & Coho s
Laye /
Va ian
P o ocol
elemen s
P ima y
physiological
endpoin s
Acquisi ion
windows &
iming
Ins umen
a ion &
logging
Sa e y
moni o s
Second
a y
ou com
es
Coho
applicabi
li y
P og ession
ules
Acous ic/
Vocal
Laye
~0.1 Hz
pacing;
exhale:
inhale 2:1–
3:2;
humming/ o
ning/singing
a
com o able
SPL; nasal
inhale,
oiced
exhale; 2–8
min se s wi h
30–60 s es s
HRV: RMSSD,
HF;
Respi a ion:
a e, a iabili y,
E CO₂
5-min HRV
segmen s
a e 60–90 s
a e
s abiliza ion;
exhale-
locked HEP
blocks i
EEG
collec ed
Ches /abdo
men bel +
PPG/ECG
(≥250 Hz
PPG o
≥500 Hz
ECG);
E CO₂
nasal
cannula (i
a ailable);
au o-
logged
cadence
E CO₂
35–45
mmHg
a ge ;
s op o
dizziness/
pa es hesi
a; ocal
s ain
check
A ec i
e
alence/
a ousal
(SAM),
pe cei e
d calm;
adhe en
ce
minu es
a a ge
a e
Neu odi
e gen ;
pos -
i al;
heal hy
mechanis
m
Inc ease se
leng h by 1–2
min when
RMSSD median
≥ session a ge
o ≥3 sessions;
add low-
ampli ude ocal
ha monics i no
h oa a igue
Mechani
cal Laye
— OPEP
Oscilla o y
exhala ion
wi h de ice
(e.g.,
Acapella/Flu
e );
esis ance
pe
manu ac u e
; 10–20
b ea h cycles
× 2–3 se s;
pai wi h
nasal inhale
Respi a ion:
a e, a iabili y,
E CO₂;
Pulmona y:
FEV₁ o peak
low; HRV:
RMSSD
(op ional)
HRV: 3–5
min
immedia ely
pos -se ;
spi ome y
p e/pos
block; E CO₂
con inuous
du ing se s
OPEP
de ice;
handheld
spi ome e
o peak-
low me e ;
PPG/ECG;
E CO₂ line
E CO₂ no
< 33
mmHg;
cough
a igue
sco e;
SpO₂ ≥
94% a
es
Dyspne
a
(Bo g),
cough
coun s
o LCQ;
spu um
olume
(op iona
l);
adhe en
ce
Pos -
i al;
ch onic
ai way
disease;
heal hy
mechanis
m
Inc ease
esis ance one
s ep when SpO₂
s able and Bo g
≤ a ge ac oss
wo sessions;
ex end se coun
i peak low +5–
10% om
baseline
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Mechani
cal Laye
— IMT
Th eshold o
elec onicall
y i a ed
inspi a o y
load a 40–
60% MIP
(p og essi e
); 30
b ea hs/sessi
on; 5–7
days/week
S eng h:
MIP/MEP;
HRV: LF/HF,
RMSSD
(op ional);
Respi a ion:
a e
MIP/MEP
weekly;
HRV 5-min
sea ed
p e/pos once
weekly;
b ea hing
a e logged
each session
IMT
aine ;
mou hpiece
wi h nose
clip;
PPG/ECG
S op o
dizziness
o ches
pain; HR
> 85%
age-
p edic ed
max; BP >
160/100
Dyspne
a,
a igue
scales;
6MWT
(op iona
l);
adhe en
ce
Pos -
i al;
decondi i
oned;
heal hy
mechanis
m
+5–10% MIP
p og ession
when echnique
s able and no
ad e se signs
o ≥3 sessions;
add esonance
block a e IMT
once RR ≤
10/min
Feedbac
k
Deli e y
— XR
Visual/audi
o y
bio eedback
in imme si e
scene; a ge
6 b /min;
paced cues +
HRV a ge ;
s ess-
con ex d ills
(op ional)
HRV: RMSSD,
HF;
Respi a ion:
a e/ a iabili y;
E CO₂ (i
ins umen ed)
HRV epochs
o 3–5 min
du ing
s eady
scenes;
e en - ag
segmen s
du ing s ess
d ills
HMD +
ches bel +
inge
PPG;
op ional
E CO₂ line;
session
analy ics
(minu es a
a ge )
Cybe sick
ness
sc een;
E CO₂ i
hype en
ila ion
isk; eye
s ain
b eaks
P esenc
e, mind-
wande i
ng,
usabili
y
(SUS),
ans e
ask
pe o m
ance
Neu odi
e gen
(engagem
en ),
heal hy
mechanis
m;
selec i e
pos - i al
Ad ance scene
di icul y when
≥15 min/week a
a ge a e o 2
weeks and
RMSSD end ↑;
in oduce s ess-
con ex module
wi h s op- ules
Feedbac
k
Deli e y
—
Con en i
onal
Desk op o
mobile
bio eedback;
paced
ci cle/ one;
a ge 6
b /min wi h
exhale bias;
weekly
e iew
HRV: RMSSD,
HF;
Respi a ion:
a e/ a iabili y;
E CO₂ (i
a ailable)
Same as XR;
weekly 20–
30 min dose
agg ega ed
Ches bel
+
PPG/ECG;
app
logging;
op ional
E CO₂
As abo e;
limi
b ea h
holds;
a oid
Valsal a
S a e
anxie y
(STAI-
S), sleep
quali y;
adhe en
ce
Neu odi
e gen ;
pos -
i al;
heal hy
mechanis
m
Inc ease daily
dose by 5 min
when adhe ence
≥80% and
RMSSD median
↑ ac oss las 3
sessions; add
humming
o e lay i
pla eau
Al e ed-
S a e
Va ian
—
HVB+m
usic
Cyclic high-
en ila ion
wi h
e oca i e
music; 15–
30 min;
supe ised;
s uc u ed
eco e y
wi h slow
esonance
Imaging: ASL-
CBF (insula↓,
amygdala/hippo
campus↑
expec ed);
HRV: acu e
RMSSD/HF↓;
Respi a ion:
E CO₂
ASL p e/ un;
HRV/E CO₂
con inuous;
eco e y
HRV 5–10
min pos
MRI
( esea ch);
E CO₂;
ECG/PPG;
audio
iming log
CO₂
moni o in
g
manda o
y;
panic/dizz
iness s op-
ules;
supine
sa egua d
s pos - un
Al e ed-
s a e
scales
(e.g.,
OBN),
ea /a e
c
change;
eco e
y
com o
Heal hy
mechanis
m;
selec i e
pos - i al
wi h
cau ion;
no i s -
line
neu odi e
gen
In oduce only
a e baseline
esonance
compe ence; cap
a 1
session/week;
ollow wi h 5–
10 min
esonance o e-
es ablish RSA
IV. RESULTS
A) E idence map. Ac oss he i e domains, included s udies concen a ed in heal hy adul samples wi h smalle bu no able
ep esen a ion o pos - i al coho s and limi ed inclusion o neu odi e gen popula ions; domain co e age clus e ed mos densely
in aVNS, acous ic/ ocal pacing nea 0.1 Hz, and espi a o y ools, wi h ewe bu me hodologically in o ma i e epo s in VR/AR
bio eedback and al e ed-s a e b ea hwo k wi h music. Endpoin classes we e ancho ed in hea - a e a iabili y (HRV; RMSSD, HF
powe , LF/HF), espi a ion me ics ( a e, a iabili y, end- idal CO₂), spi ome y and espi a o y muscle s eng h (FEV₁, FVC,
MIP/MEP), EEG HEP, and ASL-MRI ce eb al blood low. Risk-o -bias app aisal indica ed gene ally low o some conce ns o
andomized aVNS and OPEP/IMT ials, some conce ns o mode a e isk o c osso e and small mechanis ic s udies, and ypical
he e ogenei y in XR ials due o in e en ion di e si y. S udies ha explici ly con olled o epo ed b ea hing pa ame e s du ing
HRV acquisi ion p esen ed mo e in e p e able au onomic ou comes han s udies wi hou espi a o y con ol, consis en wi h ecen
psychophysiology epo ing guidance. Acous ic/ ocal s udies ou inely speci ied pacing a o nea 0.1 Hz wi h clea espi a o y
coupling and ca dio espi a o y cohe ence, whe eas aVNS s udies a ied in equency, pulse wid h, du y cycle, and mon age. XR
bio eedback epo s showed consis en measu emen o HR and HRV bu a iable documen a ion o adhe ence and dose, wi h
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Page 898 o 905
se e al ials adding usabili y indices and ans e asks unde s ess. Al e ed-s a e b ea hwo k wi h music con ibu ed ASL-MRI
pe usion mapping aligned o subjec i e in ensi y and concu en au onomic change. Exac s udy coun s, popula ion dis ibu ions,
endpoin allies, and isk-o -bias s a a a e abula ed in he e idence ma ix e e enced in Me hods.
B) aVNS: pooled au onomic e ec s and pa ame e – esponse pa e ns. Di ec ional syn hesis ac oss sham-con olled RCTs and
c osso e ials indica ed sho - e m HF-HRV and/o RMSSD inc eases unde ac i e aVNS ela i e o sham in a subse o p o ocols,
wi h age mode a ing e ec magni ude in one RCT whe e olde adul s exhibi ed la ge HF gains (Gianlo enço e al., 2024) (Table
2). Pa ame e -sensi i i y wo k showed ha speci ic equency–pulse-wid h combina ions (e.g., 10 Hz × 250–500 µs; 25 Hz × 100
µs) ele a ed SDNN wi hou eliably changing RMSSD, sepa a ing e ec s on o al a iabili y om e ec s on agally media ed ime-
domain indices (A anacko e al., 2025). A one-week daily aVNS egimen imp o ed VO₂peak and peak wo k a e while a enua ing
in lamma o y eac i i y in a c osso e ial, sugges ing bene i s ha ex end beyond es ing HRV and in o exe cise pe o mance and
immune modula ion (Ackland e al., 2025). In con as , a sepa a e c osso e s udy epo ed acu e RMSSD and HF educ ions du ing
aVNS wi hou hea - a e change, a pa e n consis en wi h mild a ousal om agal a e en ac i a ion and unde sco ing con ex -
and pa ame e -dependen he e ogenei y (Kaduk e al., 2025). Mon age conside a ions a o ed agus/cymba conchae placemen s
o e behind-ea si es o HRV modula ion in compa a i e wo k, aligning wi h au icula agal inne a ion densi y (Pe cin e al.,
2024). Taken oge he , pooled di ec ion and mode a o analysis suppo a pa ame e – esponse su ace in which equency, pulse
wid h, du y cycling, and mon age join ly de e mine whe he SDNN-dominan o RMSSD/HF-dominan changes eme ge. P o ocols
ha cons ained o paced b ea hing du ing HRV acquisi ion yielded clea e agal e ec s han p o ocols wi h spon aneous
espi a ion. These indings mo i a e pa ame e ized aVNS ials ha p e-speci y espi a o y con ol and mon age o esol e mixed
HRV di ec ionali y (A anacko e al., 2025; Gianlo enço e al., 2024; Kaduk e al., 2025).
Table 2. aVNS Pa ame e –Response Ma ix (2022–2025)
S udy
( i s
au ho ,
yea )
Popula i
on & N
(age)
Mon
age &
Side
F e
q.
(Hz
)
Pul
se
wid
h
(µs)
Du y
cycle
Cu en /
i a ion
Session
dose
Respi a
ion
con ol
P ima y
au onomic
endpoin s
(ΔRMSSD,
ΔHF, ΔSDNN;
esp–HR
coupling)†
Mode a o s /
No es
Gianlo
enço,
2024
Heal hy
adul s,
n≈44
(~40y)
Bila .
cymb
a
30
NR
Con in
uous
~1.0 mA;
pe cep ual
60 min ×1
No;
E CO₂ N
HF ↑ (SMD
NR); RMSSD
—; SDNN —
Age e ec :
la ge HF gains
in olde adul s;
(a)(b)
A anac
ko ,
2025
(a m A)
Heal hy
adul s,
n≈78
(20–35y)
Conc
hal
egion
(side
NR)
10
250
15 min
NR;
pe cep ual
15 min ×1
No;
E CO₂ N
SDNN ↑;
RMSSD —; HF
—
Pa ame e -
sensi i e
SDNN-only
gain; (a)(b)
A anac
ko ,
2025
(a m B)
Same
Conch
al
(NR)
10
500
15 min
NR
15 min ×1
No;
E CO₂ N
SDNN ↑;
RMSSD —; HF
—
As abo e; (a)(b)
A anac
ko ,
2025
(a m C)
Same
Conch
al
(NR)
25
100
15 min
NR
15 min ×1
No;
E CO₂ N
SDNN ↑;
RMSSD —; HF
—
As abo e; (a)(b)
Acklan
d, 2025
Heal hy
adul s,
n≈28 (x-
o e )
Bila .
agu
s
NR
NR
30-
min
daily
NR
30 min ×7 d
(210 min)
—
HRV NR
Ca dio espi a o
y &
immunomodula
o y bene i s
Kaduk,
2025
Heal hy
adul s,
n≈36 (x-
o e )
Cymb
a
(le / i
gh )
25
250
30s on
/ 30s
o
Pe cep ual
30 min ×1
No;
E CO₂ N
RMSSD ↓, HF
↓; SDNN —
A e en a ousal
e ec ; (a)(b)
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Page 899 o 905
Pe cin,
2024
(in-ea )
Heal hy
adul s,
n≈xx
In-ea
( agu
s/cym
ba)
NR
NR
NR
NR
NR
No;
E CO₂ N
RMSSD ↑; HF
—; SDNN —
Mon age
compa ison
a o s in-ea ;
(a)(b)
Pe cin,
2024
(behind
-ea )
Same
Behin
d-ea
NR
NR
NR
NR
NR
No;
E CO₂ N
RMSSD —; HF
—; SDNN —
Minimal
au onomic
e ec ; (a)(b)
Maes i
, 2024
Heal hy
& HF
pa ien s
(subse
heal hy
shown)
NR
(au ic
ula )
Op i
miz
ed
(NR
)
NR
NR
NR
NR
No;
E CO₂ N
RMSSD ↑ / HF
↑ (p o ile
imp o emen )
“Op imized”
s imula ion
imp o ed
ca diac
au onomic
p o ile; (a)(b)
C) Acous ic/ ocal s udies: esonance-paced RSA and a ec . Mechanis ic in es iga ions con e ged on consis en RSA
enhancemen when humming, oning, o singing was paced a app oxima ely 0.1 Hz, wi h magni ude compa able o o sligh ly
exceeding silen paced b ea hing in some compa isons (Tanzmeis e e al., 2022). Field and labo a o y assessmen s o humming and
b ie OM chan ing egis e ed highe SDNN/HF, lowe s ess indices, and lowe hea a e ela i e o ac i e s esso s and ou ine
ac i i ies, wi h bene i s some imes app oaching sleep-le el au onomic calm (Inba aj e al., 2022; T i edi e al., 2023). Vocaliza ion
in oduced posi i e a ec shi s beyond au onomic change, likely ia embodied esonance and p edic able soma osenso y eedback,
a pa e n no ed in paced singing expe imen s (Tanzmeis e e al., 2022). Respi a o y coupling was explici : p o ocols en o ced slow
cycles wi h ex ended exhala ion and, in humming, phona ion ha s abilized ai low and la yngeal con igu a ion, he eby augmen ing
espi a o y sinus a hy hmia. Rela i e o silen pacing, ocaliza ion deli e ed mul imodal inpu s (acous ic, ac ile, p op iocep i e)
ha may sca old adhe ence and in e ocep i e salience du ing p e-ac i a ion and in eg a ion phases in Resonan B ea hwo k. S udies
wi h explici espi a o y con ol and clea pacing speci ica ions p oduced he mos in e p e able RSA ou comes; he e ogenei y
inc eased when ocaliza ion s yle, loudness, o pacing d i ed. The collec i e pa e n suppo s ocal p e-ac i a ion as a low-ba ie
ou e o ini ia e agal engagemen and paced singing du ing in eg a ion o sus ain esonance wi h a ec i e bene i s (Inba aj e al.,
2022; Tanzmeis e e al., 2022; T i edi e al., 2023). Fu u e wo k should o mally con as silen e sus ocal esonance a equi alen
E CO₂ o isola e phona ion-speci ic con ibu ions.
D) In e ocep ion: phase-dependen gains and neu al coupling. Con e gen e idence demons a ed exhala ion-dependen
imp o emen s in in e ocep i e pe o mance and co ical p ocessing: hea bea -e oked po en ial ampli ude and hea bea de ec ion
accu acy ose du ing exhala ion unde in e ocep i e a en ion (Zacca o e al., 2024). A mul i-da ase beha io al analysis showed
ha espi a o y phase app oxima ely wo seconds be o e esponse p edic ed luc ua ions in esponse speed and accu acy, indica ing
a sys ema ic, ime-lagged b ea h–cogni ion coupling ha can be le e aged in cue iming (Ha ing e al., 2025). B ea h- ocused MRI
e ealed widesp ead co ical deac i a ion wi h p ese ed o s eng hened ACC–do sal a en ion connec i i y du ing b ea h
awa eness, especially in indi iduals wi h highe in e ocep i e sensibili y, consis en wi h a quie ye a en i e co ical mode du ing
slow b ea hing p ac ice (Fa b e al., 2023). Neu al synch ony wo k epo ed espi a ion-en ained del a– he a oscilla ions in limbic–
insula ne wo ks unde oli ional slow b ea hing, o e ing a mechanism o a en ional s abiliza ion and enhanced bodily signal gain
du ing esonance pacing. Dis inguishing in e ocep i e accu acy ( ask pe o mance) om in e ocep i e awa eness (sel - epo ) was
c i ical, because accu acy gains acked phase and iming, whe eas awa eness shi s mapped o ne wo k-le el engagemen . Ac oss
s udies, p o ocols aligned exhale-weigh ed iming and slow cycles o maximize pe cep ual and co ical ecep i i y o in e ocep i e
signals. These esul s jus i y exhale-locked d ills, hea bea - ocused asks embedded wi hin slow b ea hing, and ou come se s ha
include bo h HEP and beha io al accu acy. The pa e n s eng hens he a ionale o an in e ocep ion module wi hin Resonan
B ea hwo k ha explici ly con ols espi a o y phase and a e (Fa b e al., 2023; Ha ing e al., 2025; Zacca o e al., 2024).
E) Respi a o y ools: pulmona y ou comes wi h au onomic co-signals. Randomized e idence in COPD indica ed ha oscilla o y
PEP (Acapella) imp o ed cough-speci ic quali y o li e, educed objec i e 24-hou cough coun s, and enhanced a igue and gene ic
heal h indices o e h ee mon hs, consis en wi h e ec i e ai way clea ance and symp om elie (Alghamdi e al., 2023). A six-
mon h pilo in b onchiec asis epo ed ewe exace ba ions, imp o ed disease-speci ic quali y o li e, and ansien spu um inc eases
wi h wice-daily Flu e use, aligning wi h expec ed mobiliza ion e ec s (Kim e al., 2023). On au onomic endpoin s, a ou -week
RCT in obese young adul s demons a ed ha inspi a o y muscle aining inc eased MIP and p oduced a dec ease in LF/HF, a shi
owa d pa asympa he ic balance wi hou spi ome ic change (Sa-nguanmoo e al., 2025). An RCT in pos -COVID eco e y showed
ha home-based IMT imp o ed b ea hlessness and espi a o y-muscle unc ion, c ea ing a pla o m o u u e ials o add HRV
and in e ocep i e endpoin s (McNa y e al., 2022). Al hough many ai way-clea ance ials did no include HRV, mechanis ic
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easoning and a ailable da a sugges ha p olonged, esis i e exhala ion wi h OPEP and ba o e lex-salien inspi a o y loading wi h
IMT can suppo RSA and sympa ho agal ebalancing when embedded in esonance-paced sessions. De ice s udies ha eco ded
es ing HR o HRV occasionally indica ed a o able shi s, bu ou ine au onomic measu emen emains limi ed. Wi hin he
Resonan B ea hwo k amewo k, OPEP and IMT popula e he mechanical laye , wi h spi ome y and MIP/MEP as p ima y
endpoin s and HRV as a ecommended co-measu e o u u e p o ocols (Alghamdi e al., 2023; Kim e al., 2023; McNa y e al.,
2022; Sa-nguanmoo e al., 2025). S anda dized epo ing o espi a o y a e and E CO₂ du ing HRV acquisi ion would imp o e
in e p e abili y.
F) XR bio eedback: physiological pa i y, engagemen ad an age. A 2024 me a-analysis o VR b ea hing in e en ions e sus
non-VR analogues ound no signi ican di e ences in men al-heal h ou comes o physiologic measu es (hea a e, HRV), indica ing
non-in e io i y o imme si e deli e y a he session le el (Co ez-Vázquez e al., 2024). Single-case aining wi h police ins uc o s
showed ha closed-loop b ea h bio eedback inside an ecologically alid VR ac ion ask imp o ed slow-b ea hing con ol, inc eased
low- equency HRV du ing play, and enhanced decision pe o mance, sugges ing skill ans e unde s ess (Michela e al., 2022).
XR epo s equen ly documen ed high engagemen and adhe ence, wi h use p esence and educed mind-wande ing ci ed as
p ac ical bene i s ha may sus ain p ac ice dose e en i acu e physiology equals non-VR p ac ice. T ials a ely isola ed bio eedback
con en om o he VR design elemen s, con ibu ing o he e ogenei y and limi ing p ecise a ibu ion o e ec s. O e all pa e ns
suppo XR as a deli e y ampli ie o he bio eedback-suppo ed pacing laye , pa icula ly whe e s ess-con ex ans e is a p io i y,
a he han as a ca ego ical enhance o physiologic endpoin s o e con en ional bio eedback (Co ez-Vázquez e al., 2024; Michela
e al., 2022). P og ams ha include s anda dized HRV acquisi ion, explici b ea hing a ge s, and adhe ence logging o e clea e
in e ence han wellness-s yle apps wi hou physiological da a. The e idence suppo s pa i y in acu e physiologic egula ion, wi h
supe io engagemen ha may magni y cumula i e bene i s h ough highe p ac ice olume.
G) Neu oimaging o high- en ila ion b ea hwo k plus music: pe usion–phenomenology coupling. A mul imodal in es iga ion
o high- en ila ion b ea hwo k wi h music mapped ASL-MRI pe usion dec eases in le pos e io insula and pa ie al ope culum
alongside pe usions inc eases in igh amygdala and an e io hippocampus, wi h egional changes acking oceanic boundlessness
(uni y/bliss) a ings and concu en HRV dec eases indica i e o sympa he ic ac i a ion du ing induc ion (Ka a e al., 2025).
Pa icipan s epo ed educed ea and nega i e a ec a e sessions despi e ansien physiological a ousal, aligning wi h a
con olled ho me ic s ess in e p e a ion. The pe usion signa u e complemen s slowe esonance p ac ices ha emphasize RSA
enhancemen and a en ional quie ing, implying a espi a o y-neu al con inuum in which di e en dosing egimens a) bias
pa asympa he ic cohe ence and in e ocep i e salience ( esonance pacing) o b) ansien ly upshi a ousal o engage limbic
p ocessing and emo ional elease (al e ed-s a e induc ion). The s udy p o ides egion-speci ic imaging ancho s (insula down-shi ;
amygdala–hippocampus up-shi ) ha can guide ou come selec ion in u u e p o ocols es ing laye ed sequences. Au onomic and
imaging co a ia ion s eng hens he case o mul i-modal measu emen packages ha ack HRV–E CO₂ oge he wi h ASL-MRI
whe e easible. The pa e n sugges s ha in eg a ion phases could inco po a e music- acili a ed b ea hing o ha ness emo ional
p ocessing, ollowed by esonance pacing o consolida e agal eco e y. While sample sizes we e modes and music con ols
limi ed, he esul s es ablish a es able neu al model o b ea h-induced al e ed s a es ha is complemen a y o esonance-paced
in e en ions (Ka a e al., 2025).
V. DISCUSSION
The condi ions unde which aVNS and acous ic/ ocal s imula ion p oduce eliable sho - e m inc eases in agal indices and
espi a ion coupling a e inc easingly mappable o conc e e pa ame e windows and deli e y choices. Randomized e idence indica es
ha aVNS can aise HF-HRV acu ely ela i e o sham, wi h age ac ing as an e ec modi ie ha enla ges bene i s in olde adul s
(Gianlo enço e al., 2024). Pa ame e -sensi i i y wo k sugges s ha 10 Hz×250–500 µs and 25 Hz×100 µs combina ions
p e e en ially ele a e SDNN wi hou consis en ly shi ing RMSSD, implying pa ial dissocia ion be ween o al a iabili y and
agally media ed ime-domain indices (A anacko e al., 2025). A 7-day c osso e ial complemen s hese au onomic indings by
showing inc eased VO₂peak and blun ed in lamma o y esponses a e daily aVNS, si ua ing nonin asi e agal neu omodula ion
wi hin a ca dio espi a o y pe o mance ame (Ackland e al., 2025). Ye , he e ogenei y ma e s: a c osso e s udy epo ed
dec eases in RMSSD and HF du ing aVNS, compa ible wi h mild a ousal om agal a e en ac i a ion and unde sco ing he need
o s anda dize espi a ion con ol and dosing (Kaduk e al., 2025). Mon age also shapes ou comes; in-ea ( agus/cymba) placemen s
p oduced s onge RMSSD e ec s han behind-ea s imula ion in single-blind andomized es ing (Pe cin e al., 2024). Con e ging
mechanis ic s udies show ha paced singing o humming a ~0.1 Hz obus ly augmen s RSA—o en ma ching he au onomic
bene i s o silen esonance b ea hing while adding posi i e a ec —making ocaliza ion a p ac ical p e-ac i a ion and in eg a ion
ool in laye ed p o ocols (Tanzmeis e e al., 2022; Inba aj e al., 2022; T i edi e al., 2023). Toge he hese da a ad ise in-ea
mon age, ca e ul equency/pulse-wid h selec ion, explici espi a o y con ol, and he s a egic use o 0.1 Hz ocaliza ion o
maximize esonance and agal exp ession.
