intro to sound and hearing Flashcards
define timbre, frequency and amplitude
timbre: quality of a sound. refers to the characteristic of sounds, that are manipulated by vocal cords. two instruments can play the same note but sound different.
frequency: refers to pitch of the sound, it’s also the number of cycles or oscillations per second
ie every 200 Hz spacing is greater than if it was every 100Hz
amplitude: refers to the strength of a sound contributing to its loudness.
what are the three broad classes of sound in the
world around us
periodic, aperiodic and transient (periodic or aperiodic)
what is periodic sounds?
They are repetitive in nature, exhibiting regular patterns of oscillations. giving rise to fundamental frequency. periodicity: a regular, repetitive pattern.
They have distinct harmonics that are integer multiples of the fundamental frequency.
what are aperiodic sounds?
The sounds lack regular repetition and do not have a clear fundamental frequency, which means they do not have clear, distinct harmonics. They are described as random. They contain fluctuating frequencies and irregular waveforms—not equal amplitude.
what is a pure tone?
it is a type of periodic sound that has a regular repeating pattern and a single frequency with a regular waveformwith a single frequency and thus single harmonic.
Pure tones do not occur in nature as natural sounds are a combination of multiple frequencies.
what is fourier’s analysis?
It is the breakdown of complex sounds according to the different frequency components it is made up of.
viewing the harmonics, frequencies present, and waveform.
how to workout Frequency from a period of 5 milliseconds
1/5= 0.2, then multiply by 1000 to give 200 Hz
what’s the difference between period and periodicity?
a period is the time for a single wave to pass in a repetitive, regular manner
periodicity is when multiple wave pass in a repeating, regular manner
What is likely to be seen in the time and frequency domain for both aperiodic and periodic sounds?
aperiodic time domain: irregular waveforms, not repeating very random. no periodicity as its not repeating
aperiodic freq domain: no harmonics/ straight line present. all frequencies present in a fluctuating maner with irregular amplitudes.
vice versa for periodic
what are harmonics?
integer multiples of the fundamental frequency
200,400,600,800,1200
what are formants?
the positions of the highest power in the spectral envelope of a sound signal.
it distinguishes vowels from each other
what is a spectrogram?
combines information from the time and frequency domains.
there’s a colour coded axis indicating the intensities of the frequencies present.
the brightest areas on spectrogram correspond to the highest power in the spectral envelope of a sound/ vowel ie formants allowing the discrimination between vowels and sounds
what frequencies are humans most sensitive to
between 20hz and 20khz or 20000 hz
what is the threshold frequencies that humans can hear
20 Hz to 20 kHz
what is the conversation speech frequencies that humans are sensitive to
in the range of 250 – 4,000 Hz, where important information in conversational speech tends to be
