pitch, loundess and timbre

Question 1

are pitch and frequency subjective or objective?

Answer 1

pitch is subjective, associated with periodic sounds travelling outward from a sound source
frequency is objective

Question 2

what is a harmonic series?

Answer 2

a set of frequencies which are all integer multiples of the lowest, fundamental frequency.
eg. f1 = 200 Hz
f2 = 400 Hz
f3 = 600 Hz
….

Question 3

what is special about the spectrum of a periodic vibration?

Answer 3

it’s a harmonic series!
a series of narrow peaks centred on a harmonic series

Question 4

how does the brain identify pitch?

Answer 4

it searches for a pattern of harmonic frequency components.
once a harmonic series is found, a single pitch is normally identified. this pitch is the same as the fundamental pitch.

Question 5

what is the basic unit of pitch? what is the frequency ratio of two tones separated by it?

Answer 5

the basic unit of pitch is the **octave*
two tones separated by an octave have a frequency ratio of exactly 2

Question 6

what is the formula for pitch interval between two frequencies?

Answer 6

1200/log10(2) * log10(f1/f2)

given in cents

Question 7

are loudness and acoustic pressure subjective or objective?

Answer 7

loudness is subjective and related to the intensity of a perceived sound
(also depends on the frequency content of the sound, as the ear is not equally sensitive to all frequencies)

acoustic pressure is objective

Question 8

what is the formula for finding intensity I for an isotropic sound source of power P

Answer 8

I = P/4pi*r^2

Question 9

what is the formula for intensity level?

Answer 9

IL = 10log10*( I / I(0) ) dB

where I(0) = 10^-12 W/sq m.

Question 10

what is the formula for sound pressure level? (SPL)

Answer 10

SPL = 20log10 * ( p(RMS) / p(0) ) dB

Question 11

what does each point on an N phon equal loudness contour represent?

Answer 11

a sine wave sound that has the same perceived loudness as a 1000 Hz tone with SPL of N dB