Sound Express™: Phone Module
This module is very similar to the basic module except that the frequency range of all acoustic sounds is limited to telephone bandwidth (300-3200 Hz). Here summerize the training groups in this module:
Group 1: Pure Tones – practice identifying different pitches of sound.
All the pure tones within the frequency range of 300-3200 Hz is not affected. However, any pure tones out of this range will be severely attenuated. The listeners may not be able to hear any sounds out of this range. Some performance degradation is expected with this training group. Since some sounds are highly attentuated, the training will help the listener recognize the very soft sound.
Group 2: Environment Sounds – practice identifying common environment sounds
There will be no big problem to recognize the environment sounds that have limited high frequency components. However, the recognition performance of those environment sounds that highly depend on the high frequency components will be significantly reduced. It is expected that overall recognition performance will be reduced with bandlimited speech. The training will help the listener focus on the available spectral cues and discriminate different sounds with limited spectral information.
Group 3: Male/Female Identification - practice discrimination between speakers
Recent studies showed that the voice gender recognition can be significantly affected by bandlimiting (Horng et al., Ear and Hearing, 28(2), Suppl. 66S-69S). It is not possible that the spectral shape help the recognition of voice gender and the loss of high frequency information weakens the spectral contrast and results in a lower recognition performance. The training will let the listener more focus on the periodicity cue to discriminate different voice gender and improve the overall recognition performance of voice gender recognition.
Group 4: Vowel Recognition - practice vowel discrimination and identification
Vowel recognition is highly dependent on the F1 and F2. Since both these two formant frequencies are within the telephone bandwidth. Vowel recognition performance is not significantly affected by bandlimiting for English. However, vowel recognition performance is significantly reduced with telephone speech for Chinese. One reason is that some Chinese vowels are dependent on the spectral difference in the high frequency region (e.g. YI versus YU). The loss of high frequency information makes it diffciult to discriminate these vowels.
Group 5: Consonant Recognition - practice consonant discrimination and identification
Consonant recognition is highly dependent on the high frequency components. The loss of high frequency components in these bandlimiting speech will significantly reduce the recognition performance of consonants. Recent studies did reveal that consonant recongition is highly affected by bandlimiting. The training will help the listener to pay more attention to other available cues to discriminate different consonants.
Group 6: Word Discrimination – practice common words from four different topic categories
Word recognition will be affected by the loss of high frequency components in the telephone speech since words generally include both vowel segments and consonant segment. Since the English vowel recognition is not affected by telephone bandwidth, the performance will be highly dependent on the consonants. Some words will be more affected by bandlimiteing than the other words. The training, again, will allow the listener to utilize the available spectral cues to discriminate different words.
Group 7: Everyday Sentences – practice identifying sentences with different levels of background noise
Sentence recognition is one of the tests which will be most affected by bandlimiting. Recent studies show a near 20% drop in recogition performance with limited bandwidth. The training will allow the listener to utilize the available spectral cues to understand the sentences.
Group 8: Music Appreciation – practice identifying musical instruments and familiar tunes as a start to music appreciation.
Depending on the frequency range of musical instruments and familiar tunes. Some musical instruments and familiar tunes may not be affected by bandlimiting if their frequency ranges are primarily within the 300-3200 Hz. Otherwise, recognition performance will be significantly impacted by the bandlimiting.