PH 105 Dr. Cecilia Vogel Lecture 10

OUTLINE  Subjective loudness  Masking  Pitch  logarithmic  critical bands  Timbre  waveforms

Multiple Sources  Multiple sources of sound  which are    If you have n equal sources   The sound level in dB  L I =  If 1 washing machine has a sound intensity level of 30dB, _ washing machines will have a level of ____, _ washing machines ____, etc  demo?

Subjective Loudness Level  The subjective loudness level of a sound  depends  depends on other properties, too,   Recall:  how well can you hear at different freq’s?  Graph from text:  each curve shows sounds of equal

Sound Level Meter Weighting  Our ears are not as sensitive to sounds at the  so very low and very high sounds have to have  to have the same  The _________ on sound level meter mimics this:  meant to give _______ to sounds that sound  even if the

Masking  Recall figure from text  gives levels of  if that pure tone is.  Background noise can  making them _____________ even above the  Count how many tones you can hear  In the 2 nd case the note was _____than the masking noise,  Noise can more easily mask a

Pitch  Pitch depends most strongly on   Note period of wave may  period always is

Logarithmic Sensations  The highest pitch we hear  does not sound  listen to tuning fork and lower pitch  Which pitch sounds the same amount higher than tuning fork?  CD demo. Which set of sounds is separated by equal intervals?  Every time we ______ the frequency or period of the sound,   Pitch is  Each doubling of frequency

Pitch and Amplitude  Sounds of the same frequency,  but one  may sound  Varies  Recall lab

Critical Bands  Much of pitch is due to  which part of  If two tones produce similar vibrations of basilar membrane  they are said to lie  A noise sounds louder if it vibrates  demo CD, noises with

Timbre  Timbre or tone quality  depends primarily on   A pure tone has a  tuning fork  complex tones have  vowel sounds, “noisemaker”, links on web  noise  H sound

More on Complex Tones  Sometimes a complex tone sounds like   if the ______of the wave  other times,  if one ____ is strong and the rest  yet other times, as  or a  if several frequencies are strong.  Depends on

Summary  Subjective sound level  two settings on dB meter  Masking: noise makes tone inaudible.  Pitch  periodicity or frequency  position on membrane – critical bands  logarithmic  Timbre  waveform  pure tones, complex tones, noise