stroke is the second leading cause of death and causes permanent disability in one - third of 
 survivors1 , 2 . many stroke patients suffer from motor impairments that limit 
 muscle control , activities of daily living , and locomotion activity . in addition , stroke 
 patients have increased double support duration , decreased cadence , shorter stride , 
 decreased stance time , and shorter lower limb joint range of motion compared to able - bodied 
 persons3,4,5 . rhythmic auditory stimulation ( ras ) uses musical stimuli to improve the gait performance of 
 patients who have neurological conditions ( e.g. , parkinson s disease , cerebral palsy , 
 traumatic brain injury , stroke)6 . because 
 music includes temporal characteristics such as anticipation and predictability7 , ras may act on the indicators that inform 
 the gait - phase sequence . stroke patients have shown better performance when engaging in 
 conventional gait training with ras versus conventional gait training only6 . for example , a stroke group that received 
 ras combined with gait training showed greater improvements in gait velocity , cadence , 
 stride length8 , and hip joint motion 
 symmetry and decreased vertical center of mass displacement9 . lee et al.10 
 reported improvements in gait symmetry , velocity , and cadence in stroke patients when gait 
 training by matching the footfall of the affected side with ras and applying baseline and 
 > 30% baseline speed . compared to the control group , the chronic stroke patients who had 
 trained with home - based auditory stimulation showed significant improvements in affected 
 side stride length , unaffected side stride length , stride length ratio , affected side single 
 support time , single support time ratio , and gait velocity11 . recently , the results of studies with auditory cueing systems for gait rehabilitation 
 training have been reported . nagano , japan)12 , 13 , which was developed to simultaneously support locomotion 
 compensation and gait rehabilitation training using ras methods . this device consists of a 
 transmitter that pairs with three - axis acceleration sensors worn on each ankle and wireless 
 headphones . muto 
 et al.13 reported a significant decrease 
 in ground - contact timing asymmetries and gait tempo fluctuation during gait training with 
 the walk - mate device in stroke hemiplegic patients . in another study , casamassima et al.14 described inertial measurement 
 units ( imu ) based on a wearable auditory feedback system that monitors gait training with 
 parkinson s disease patients . this system provides real - time audio feedback and estimates 
 spatiotemporal gait parameters via gait event data detected from imu sensors mounted on both 
 shoes . the advantages of the application include its 
 portability , simple configuration , inclusion of various auditory stimuli , and ease of saving 
 real - time data . this device type must have the capacity to be used during gait training 
 anywhere at any time . in this study , two aspects of our smartphone - based ras application 
 were investigated : ( 1 ) the effects of various ras tempos on stroke gait patterns and ( 2 ) the 
 effects of short - term gait training on spatiotemporal gait parameters in stroke 
 patients . the inclusion criteria 
 were as follows : at least 6 months since stroke , no visual or auditory deficits , and 
 independent gait > 10 meters . the general characteristics of the study participants are 
 detailed in table 1table 1.participant informationparticipants ( n=15)gender ( m / f)11/4age ( years)56.0 ( 7.4)height ( cm)167.7 ( 7.7)weight ( kg)68.3 ( 8.2)paretic side ( left / right)8/7since onset ( months)81.9 ( 87.8)mmse - k28.4 ( 2.1)mbi96.3 ( 4.4)values are means ( sd ) . mmse - k : mini mental state examination - korean version , mbi : 
 modified barthel index . the institutional review board of the korea national rehabilitation center 
 approved the study protocol . the purpose and procedures of the study were fully explained , 
 and all participants were required to provide informed consent . mmse - k : mini mental state examination - korean version , mbi : 
 modified barthel index gait training with ras was performed in an unobstructed space and additional auditory 
 stimuli were blocked in order for subjects to concentrate on the ras sound . each ras 
 condition was practiced for 10 minutes . a 3-minute adaptation period and a 7-minute 
 gait - training period all subjects walked at a comfortable speed three times , 
 after which their mean cadence ( baseline ) was calculated and converted to 10% , 5% , 0% , 
 + 5% , and + 10% of baseline . the mean cadence was calculated by averaging three 10-meter walk 
 individual times , while subtracting the acceleration and deceleration periods . the ras application has seven sound sources ( c - e - g , c - f - a , a - d - g , clap , click , gun , and 
 robot ) that could be selected and applied based on the user s preference . to adapt to the 
 ras sounds , participants listened to the rhythm of the application and were instructed to 
 tap their fingers in their lap or stamp their feet when in a seated position . then , subjects were asked to 
 listen carefully to the rhythm of the ras application and heel strike to the sounds . ten - minute intervals between trials eliminated any remaining effects that could influence 
 the next trial . imu sensors ( shimmer3 , shimmer , dublin , ireland ) were attached above both ankle joints for 
 heel - strike detection . these sensors were connected to the ras smartphone application via 
 bluetooth , and heel - strike detection information was shown on the display as a red dot . thus , gait training focused on the timing of heel strikes on the ground and patients were 
 asked to execute heel strikes in tandem with the ras sound . a validated wireless inertial sensing device ( g - walk , bts s.p.a . the sensor was attached 
 to subjects waists ( l45 intervertebral space ) using a semi - elastic belt to determine the 
 acceleration values for three anatomical axes : anterior - posterior , medial - lateral , and 
 vertical17 . park and woo18 suggested that the g - walk represents a 
 valid method for assessing the effectiveness of clinical therapeutic interventions of gait 
 analysis . their comparative study proved that there is a significant and high correlation 
 between gait velocity and cadence and the foot pressure sensor system ( gaitrite , cir 
 systems , inc . , spatiotemporal parameters such as gait 
 speed , cadence , stride length , gait cycle duration , and step length on the affected and 
 unaffected sides were recorded . the spatial symmetry ratio was calculated by recording the 
 step length on the affected and unaffected sides . for each trial , the subjects 
 were asked to walk a level gait way ( 16 m ) . to eliminate acceleration and deceleration 
 effects , only the middle distance ( 10 m ) was used for calculations . data collection was 
 repeated three times with 3 minutes of rest between trials . to determine the effect of 
 various ras tempos on gait patterns , the kolmogorov - smirnov test was used firstly to check 
 if the data were normally distributed . secondly , a one - way repeated measures analysis of 
 variance ( anova ) and least significant difference ( lsd ) post - hoc analysis were performed . data were analyzed using spss statistics for windows , version 21.0 ( ibm corp . , armonk , ny , 
 usa ) parametersbaseline10%5%0%+5%+10%after ras trainingspeed(m / min)70.53(12.36)57.84(8.27)64.30(9.74)68.53(10.89)77.22(16.07)77.53(15.21)79.53(15.85)cadence(steps / min)51.89(6.23)46.30(5.35)48.99(6.03)51.44(6.07)53.73(6.50)55.32(6.79)53.30 ( 7.22)stride length(m)1.37(0.22)1.27(0.17)1.32(0.18)1.35(0.18)1.44(0.22)1.42(0.24)1.50(0.22)gait cycleduration ( s)1.18(0.16)1.32(0.17)1.25(0.17)1.18(0.16)1.13(0.16)1.10(0.15)1.15(0.18)step lengthaffected side ( m)0.69(0.11)0.65(0.09)0.67(0.10)0.67(0.09)0.73(0.12)0.72(0.12)0.74(0.09)step lengthunaffected side ( m)0.68(0.13)0.61(0.10)0.65(0.11)0.67(0.10)0.70(0.13)0.68(0.13)0.75(0.15)symmetry ratio(step length)1.04(0.17)1.06(0.14)1.04(0.15)1.02(0.15)1.06(0.16)1.08(0.15)1.02(0.14)values are means ( sd ) . * significantly different from baseline ( without ras ) 
 ( p<0.05 ) .   significantly different from the 10% ras condition 
 ( p<0.05 ) .   significantly different from the 5% ras condition 
 ( p<0.05 ) significantly different from the 0% ras condition 
 ( p<0.05 ) .   significantly different from the + 5% ras condition 
 ( p<0.05 ) . * * significantly different from the + 10% ras condition ( p<0.05 ) . 
  significantly different from after ras training ( without ras ) 
 ( p<0.05 ) . in the 10% ras condition , m / min , f=34.219 ) , cadence 
 ( 46.30  5.35 steps / min , f=114.253 ) , stride length ( 1.27  0.17 m , f=12.082 ) , step length on 
 the affected side ( 0.65  0.09 m , f=14.026 ) , and step length on the unaffected side ( 0.61  
 0.1 m , f=13.066 ) decreased significantly compared to baseline ( p < 0.05 ) . furthermore , 
 gait cycle duration ( 1.32  0.17  s , f=150.236 ) increased significantly compared to baseline 
 ( p < 0.05 ) . in the 5% ras condition , m / min , f=34.219 ) and 
 cadence ( 48.99  6.03 steps / min , f=114.253 ) decreased significantly , while gait cycle 
 duration ( 1.25  0.17  s , f=150.236 ) increased significantly compared to baseline ( p < 
 0.05 ) . in the + 5% ras condition , gait speed ( 77.22  16.07 m / min , f=34.219 ) and cadence 
 ( 53.73  6.5 steps / min , f=114.253 ) increased significantly , while gait cycle duration ( 1.13 
  0.16  s , f=150.236 ) decreased significantly compared to baseline ( p < 0.05 ) . in the + 10% 
 ras condition , gait speed ( 77.53  15.21 m / min , f=34.219 ) and cadence ( 55.32  6.79 
 steps / min , f=114.253 ) increased significantly , while gait cycle duration ( 1.10  0.15  s , 
 f=150.236 ) decreased significantly compared to baseline ( p < 0.05 ) . m / min , f=34.219 ) , cadence ( 53.30  7.22 steps / min , 
 f=114.253 ) , stride length ( 1.50  0.22 m , f=12.082 ) , step length on the affected side ( 0.74 
  0.09 m , f=14.026 ) , and step length on the unaffected side ( 0.75  0.15 m , f=13.066 ) 
 increased significantly compared to baseline ( p < 0.05 ) . gait cycle duration ( 0.75  
 0.15  s , f=150.236 ) decreased significantly compared to baseline ( p < 0.05 ) . values are means ( sd ) . * significantly different from baseline ( without ras ) 
 ( p<0.05 ) . significantly different from the 5% ras condition 
 ( p<0.05 ) .   significantly different from the 0% ras condition 
 ( p<0.05 ) .   significantly different from the + 5% ras condition 
 ( p<0.05 ) * * significantly different from the + 10% ras condition ( p<0.05 ) . 
  significantly different from after ras training ( without ras ) 
 ( p<0.05 ) ras is an increasingly popular form of rehabilitative exercise therapy for neurological 
 gait disorders . auditory - motor synchronization in the reticulospinal tract is the key 
 concept of ras19 . timing cues in gait 
 motion have the capacity to improve movement control and change temporal gait 
 parameters7 . several studies have 
 demonstrated the effects of ras on neurological gait disorders such as stroke , parkinson s 
 disease , and cerebral palsy . these studies reported improvements in gait velocity , stride 
 length , and cadence in response to ras rehabilitative therapeutic methods8 , 19 , 20 . however , most studies of stroke patients 
 have used ras with constant speed- or time - based stimulation increases . cha et al.21 studied the immediate effects of four ras 
 tempos ( 10% , 0% , + 10% , and + 20% ) on the gait patterns of hemiplegic stroke patients . the 
 authors reported that a faster ras tempo increased gait velocity , which indicated that there 
 was potential to immediately improve walking abilities . suh et al.22 reported improvements in gait velocity , stride length , 
 cadence , and standing balance in a group of hemiplegic stroke patients who received gait 
 training with 5% and 10% increased ras compared to a group that did not receive ras . in this study , the effect of various ras tempos on gait patterns was examined and the 
 effectiveness of short - term gait training with a smartphone - based ras application was 
 confirmed . the results showed significant differences in spatiotemporal gait parameters 
 after ras training compared with those before training . in the 10% ras condition , gait 
 speed , cadence , stride length , and step length on the affected and unaffected sides 
 decreased significantly , while gait cycle duration increased significantly . in the 5% ras 
 condition , gait speed and cadence decreased significantly , while gait cycle duration 
 increased significantly . in the + 5% and + 10% ras conditions , gait speed and cadence 
 increased significantly , while gait cycle duration decreased significantly . when the ras 
 tempo increased , all spatiotemporal gait parameters appeared to increase gradually , while 
 the gait cycle duration decreased . gait speed , cadence , and gait cycle duration showed the 
 highest significant improvement in the + 10% ras condition . after gait training with ras , 
 gait speed , cadence , stride length , and step length on the affected and unaffected sides 
 increased significantly ; gait cycle duration decreased significantly compared to that before 
 ras gait training . it is especially noteworthy that step length increased significantly not 
 only on the affected side but also on the unaffected side . increased gait speed , which is determined by cadence and stride length23 , is often an outcome measure when evaluating gait 
 function . the improvement in movement patterns activates an internal time - keeping mechanism , 
 which leads to movement synchronization24 . in our study , therefore , the spinal motor system was optimized for movement 
 patterns following the reticulospinal pathway at the brainstem level25 . suteerawattananon et al.26 reported that auditory cues can increase spinal motor neuron 
 excitability via the reticulospinal tract and decrease muscle reaction time in response to 
 motor commands , thus improving gait speed . therefore , the auditory information provides 
 stimulation that bypasses the damaged anatomy , leading to good muscle performance or timing 
 control , and modulates a motor timing - control signal that is received by the brain s 
 compensatory network . this has a useful effect on the neurological function and 
 movement - processing centers of the brain27 . in the 0% ras condition prassas et al.9 reported no 
 significant changes in stride length when baseline speed was applied with stroke patients . another study also reported no significant differences in gait parameters such as gait 
 velocity , cadence , or stride length in hemiplegic stroke patients when 0% ras was 
 applied21 . therefore , it may be 
 inferred that rhythmical tempo variations have a positive impact on the gait of stroke 
 patients . however , the equivalent rhythm to gait speed did not significantly affect the gait 
 of stroke patients . symmetry is an important factor during exercise or therapeutic treatment , particularly 
 after stroke . patterson et al . recommended that step length , stance time , and swing time be 
 used as gait parameters when determining the symmetry ratio28 . in the present study , step length as it pertained to spatial 
 symmetry was examined . symmetry ratio appeared to improve at 0% and around the 5% ras 
 condition as well as after ras training . these trends are likely related to the fact that 
 patients walked with symmetrical auditory cueing that adjusted to a comfortable walking 
 cadence . although statistically significant results were not obtained , the tendencies of the 
 spatial symmetry ratio were confirmed . further studies involving more subjects and temporal 
 symmetry factors such as stance time and swing time will be needed . the present study showed that hemiplegic stroke patients spatiotemporal gait parameters 
 change with various ras tempos . moreover , significant improvements in gait speed , cadence , 
 stride length , and step length on the affected and unaffected sides were observed after gait 
 training . previous studies of gait training with ras over the course of three weeks reported 
 significant improvements in gait velocity , stride length , cadence , and symmetry8 as well as standing balance22 for stroke patients . future studies need 
 to evaluate more patients and the long - term effects after a certain period of ras gait 
 training . a longer period of intervention could result in a higher number of positive 
 results . in the future , we plan to combine our ras system with a wearable lower - limb rehabilitation 
 robot . zanotto et al.29 examined how 
 different auditory feedback modalities in healthy subjects may affect gait modification 
 through short - term gait training using an exoskeleton robot . the authors asserted that a 
 combination of kinetic and visual guidance might be as effective as combined kinetic 
 guidance and rhythmic cues . we also hope to conduct comparative analyses with robotic 
 devices for various tempos . in this study , imu sensors were attached to both ankle joints to gather heel - strike 
 information . the acquired information , which was displayed on a smartphone , was used by the 
 participants to time their heel strikes to match the ras sound during gait training . we plan 
 to update the ras application for use not only in gait training but also during real - time 
 gait evaluation ( via calculations based on heel - strike information , including gait 
 symmetry ) . we expect the application to be useful during gait rehabilitative training and 
 that chronic stroke survivors in any environment may find it useful .
[ purpose ] the effects of various rhythmic auditory stimulation tempos on stroke gait 
 pattern changes when training patients with a smartphone - based rhythmic auditory 
 stimulation application were investigated . 
 [ subjects and methods ] fifteen patients with 
 chronic stroke were included . 
 cadence during comfortable walking was measured ( baseline ) . 
 after the baseline findings were recorded , rhythmic auditory stimulation with five 
 different tempos ( i.e. , 10% , 5% , 0% , + 5% , and + 10% change from baseline ) was randomly 
 applied . 
 finally , comfortable walking without rhythmic auditory stimulation was initiated 
 to evaluate gait pattern changes . 
 [ results ] as the tempo increased , the spatiotemporal 
 gait parameters of the stroke patients changed significantly . 
 gait speed , cadence , and 
 gait cycle duration showed the greatest improvement in the + 10% rhythmic auditory 
 stimulation condition compared to baseline . 
 after gait training with rhythmic auditory 
 stimulation , gait speed , cadence , stride length , gait cycle duration , and step length of 
 the affected and unaffected sides improved significantly compared to baseline . 
 [ conclusion ] significant changes in the gait pattern of stroke patients were noted for 
 various tempos after training with rhythmic auditory stimulation . 
 these findings could be 
 used to customize rehabilitative gait training for patients who experience stroke with 
 hemiplegia .