L2 Spectograms

Question 1

A waveform is used to look at repeating patterns of sound, and is required to calculate ________

Answer 1

Fundamental frequencies

Question 2

A spectrum is useful for looking at _________/__________

Answer 2

harmonics/harmonic frequencies

Question 3

What is the advantage of using a spectrogram?

Answer 3

We need a display that shows both:
- how the signal is changing in time
- the frequency composition of the signal (and how this changes with time)

Question 4

What do the x axis, y axis and grey scale of a spectrogram show?

Answer 4

x axis - time
y axis - frequency
grey scale - intensity

Question 5

What type of filter is required to produce a spectrogram?

Answer 5

A band-pass filter

Question 6

What is a band-pass filter?

Answer 6

A bandpass filter (BPF) is a device that passes frequencies within a certain range and rejects (attenuates) frequencies outside that range

Question 7

What is the ‘centre frequency’ of a band-pass filter?

Answer 7

Each electronic band-pass filter will have a frequency it is most sensitive to
Centre frequency – In the middle of the bandpass filter, the frequency the bandpass filter is most sensitive to.

Question 8

Can describe range of frequencies using __________. Anything that doesn’t fit within this from original sound won’t pass through and therefore won’t be in the output.

Answer 8

filter bandwidth

Question 9

A bandpass filter splits a signal into different __________

Answer 9

frequency components

Question 10

Pure tone
Spectrum here shows there’s one frequency in the sound, at 1000Hz
Spectrogram – the time in the spectrogram corresponds to the time in the waveform. The grey scale represents the intensity. No energy in the signal other than constant energy at 1000 Hz. Spectrogram for a pure tone. Region of high intensity corresponds to the frequency on the spectrum

Question 11

Does a band-pass filter tell us what exact frequencies fall within a range?

Answer 11

The filter doesn’t tell us what exact frequencies are in the range, just what is and what isn’t in the bandwidth.

Question 12

There is an intricate relationship between a spectrum and its spectrogram. The _____ on a spectrogram line up to the _____ on a spectrum

Answer 12

There is an intricate relationship between a spectrum and its spectrogram. The bands on a spectrogram line up to the peaks on a spectrum

Question 13

Do voiceless consonants have formants?

Answer 13

No

Question 14

How do the bandwidth filters in human ears differ from fixed filter bandwidths?

Answer 14

they use a variable rather than fixed filter bandwidth (bandpass filter varies along length of the cochlear)

Question 15

How can Spectrographic displays be useful to an SLT?

Answer 15

Can help identify speech abnormalities which are difficult to pick up from listening alone

Can identify that patterns of sound are different between 2 people, can quantify differences

Question 16

A digital recording is coded with ________

Answer 16

numbers

Question 17

Converting digital to analogue system requires ________

Answer 17

quantisation

Question 18

How do you ensure a good signal to noise ratio when recording sounds?

Answer 18

Recording in a quiet environment
Proper setting of recording levels

Question 19

In high quality speech recordings, we aim to increase ________ and reduce ______

Answer 19

Inhigh quality speech recordings, we aim to increase dynamic range and reduce noise