Vowel Displays as a Function of Time and Frequency

The examination of the distinguishable sound quality or timbre of vowel sounds is aided by two different types of displays of the sound. The display of the sound image as a function of time shows that the waveforms of the three vowel sounds are distinctly different. This is the most common type of display as captured by an oscilloscope or a computer display. 对元音声音可区分的音质或音色的考察，可以通过两种不同的声音显示方式来辅助。声音图像作为时间函数的显示表明三个元音声音的波形明显不同。这是最常见的一种显示方式，通常通过示波器或计算机显示来捕捉。 The second type of display shows the sound image as a function of frequency. This is an example of Fourier analysis, and these displays that show the amount of signal associated with each harmonic of the sound signal are called fast Fourier transforms, or FFTs. The FFT provides a way to quantify the differences in the harmonic content of the vowel sounds, and provides some insight into how the ear distinguishes these vowel sounds. With the insight provided by the place theory of pitch perception, it can be seen that the human ear's analysis of sound quality bears some resemblance to an FFT. 第二种显示方式将声音的图像表示为频率的函数。这是傅里叶分析的一个例子，那些显示声音信号每个谐波相关信号量的显示被称为快速傅里叶变换，或FFT。FFT提供了一种量化元音声音谐波内容差异的方法，并提供了一些关于人耳如何区分这些元音声音的见解。借助音调感知的地方理论所提供的洞察，可以发现人类耳朵对声音质量的分析在某种程度上与FFT相似。

These displays were created with MacScope2 by Elisha Huggins.

Vowel Displays as a Function of Time and Frequency

Thanks to Katherine Marks for her permission to use vowel sounds she produced to illustrate how the ear detects the difference.

The inner ear acts as a sophisticated sound analyzer, spreading out the energy content of the sound as a function of frequency. As shown here for three vowel sounds, the result is a distinguishable pattern of excitation on the basilar membrane of the cochlea. This permits the clear distinguishing of vocal sounds even if they have identical pitch and loudness.

The examination of the distinguishable sound quality or timbre of vowel sounds is aided by two different types of displays of the sound. The display of the sound image as a function of time shows that the waveforms of the three vowel sounds are distinctly different. This is the most common type of display as captured by an oscilloscope or a computer display.

The second type of display shows the sound image as a function of frequency. This is an example of Fourier analysis, and these displays that show the amount of signal associated with each harmonic of the sound signal are called fast Fourier transforms, or FFTs. The FFT provides a way to quantify the differences in the harmonic content of the vowel sounds, and provides some insight into how the ear distinguishes these vowel sounds. With the insight provided by the place theory of pitch perception, it can be seen that the human ear's analysis of sound quality bears some resemblance to an FFT.