## 4 Discussion  
### Relationship between Percentage of Articulation and \(\tau_{\text{e}}\)-med  
Individuals with normal hearing can accurately identify almost all monosyllables under quiet conditions when presented at a sufficient sound pressure level. However, the accuracy of listening decreases under noise-presented conditions [26, 27]. [PERSON] et al. evaluated the effect of noise on the \(\tau_{\text{e}}\) of monosyllables [20]. They reported that the \(\tau_{\text{e}}\) of monosyllables decreased by up to half when measured under noisy conditions and that the \(\tau_{\text{e}}\) was strongly correlated with the decrease in speech recognition in individuals with normal hearing. Other studies [11, 19, 20, 21] showed similar results under noise and reflection conditions. The \(\tau_{\text{e}}\) is one of the significant factors for estimating the speech recognition of individuals with normal hearing in various sound fields. Furthermore, a previous study reported that the \(\tau_{\text{e}}\)-med is strongly correlated with the percentage of accurately perceived articulations in patients with sensorineural hearing impairment. The \(\tau_{\text{e}}\)-med of a monosyllable represents the balance between the periodicity of the vowel and consonant components. When the vowel and consonant components of a monosyllable produce a  
Figure 3: The averaged \(\tau_{\text{e}}\)-meds of presentation and response. SRS: speech recognition scores; \(\tau_{\text{e}}\)-med: median effective duration. Values are presented as means \(\pm\) standard deviation of participants in high-, middle-, and low-SRS groups.  
Figure 2: Relationship between the percentage of articulation and \(\tau_{\text{e}}\)-med. Panels (**a**–**c**) show the results of high-, middle-, and low-SRS groups, respectively. The different symbols indicate different consonants. SRS, speech recognition score; \(\tau_{\text{e}}\)-med, median effective duration.  
stable wave at the fundamental frequency of the voice, the length of the \(\tau_{\rm e}\)-med increases [7]. Patients with sensorineural hearing impairment may recognize the stability of the temporal pattern of sound waves as a cue to identify certain monosyllables. However, previous studies did not evaluate the influence of the degree of speech recognition. Significant correlations were observed between the percentage of articulation and the average \(\tau_{\rm e}\)-med in the three SRS groups, suggesting that the stability and persistence of the temporal pattern of waves are important factors for speech recognition, even in patients with poor speech recognition. Hence, the \(\tau_{\rm e}\)-med is useful for estimating the monosyllables that patients with sensorineural hearing impairment find easy to listen to, independent of speech recognition performance.  
The most significant challenge faced by patients with sensorineural hearing impairment is understanding speech in noisy conditions [25; 26; 27; 28; 29]. The effect of noise is more pronounced in patients with sensorineural hearing impairment than in individuals with normal hearing [26; 27]. If such a relationship also holds in noisy conditions, the \(\tau_{\rm e}\)-med may be useful for estimating the monosyllables that patients with sensorineural hearing impairment find easy to hear in noisy environments. However, to the best of our knowledge, no previous study examined the relationship between the listening ability of such patients in noisy conditions and the \(\tau_{\rm e}\)-med. Further studies on the relationship between the \(\tau_{\rm e}\)-med and confusion in patients with sensorineural hearing impairment in noisy conditions are needed.