Effect of autonomic cardiac modulation on speech perception in noise

Recognizing speech in noise is affected by many physiological, psychological and environmental modulation mechanisms. The present study aimed to examine the effect of autonomic cardiac modulation on speech perception in noise (SPIN) by investigating how cardiac activity with heart rate (HR) change influences SPIN. Ten young and normal-hearing subjects were studied. There were 4 sessions for each subject. They were firstly given a 5-min rest for recording baseline HR. They were then asked to recognize a list of 20 sentences corrupted by 2-talker babble masker at -10 dB signal-to-noise ratio. The SPIN score was measured, as well as the HR which reflects the influence of noise on cardiac activity. Using the same speech recognition protocol, in section 3 and 4, SPIN and HR were measured immediately and 10 mins after each subject was asked to cycle for 5-7 minutes to experience a moderate amount of exercise. Experimental results showed that, after moderate exercise of bicycle-riding, most participants had better SPIN score in comparison with that measured before exercise (49.7% vs 42.5%). After the recovery to a normal resting cardiac activity, the SPIN performance of 49.9% was significantly better than the normal level at resting cardiac activity (p<;0.05). In summary, the present study quantitatively demonstrated the correlation between improved SPIN performance and autonomic cardiac activity.