A measure of the strength or magnitude of the sound wave
Metrics that can be used to express Amplitude
A. Instantaneous amplitude
Amplitude of waveform at some specific instant in time.
Need always to report with the angle
i.e. at 90 degree
Practice Combining Unequal Levels
What is the combined total intensity level of a dishwasher that has a 40 dB output
level and refrigerator that has a 43 dB output level?
1. Calculate the power it takes to generate each source separately
7 in-lmsih, +0
Reject or notch filter
Five Principal Parameters of Filters
Upper cut-off frequency
(-3 dB down from fc)
Exam 1 Review
Relationship between Newtons three Laws of Motion and Sound Transmission
Law 1: Objects maintain their motion without outside influence/inertia
Law 2: f=ma/
Sound results when some force is applied to the air medium
Law 3: For every act
Psychological Correlates of the Physical Attributes of Sounds
Frequency -> Pitch
Humans perceive frequencies from
20-20,000 Hz as different pitches
Frequency correlates to pitch
Intensity -> Loudness
No direct subjective correlate
Reflection of Sound Waves
With no obstacle, wave fronts would continue toward
Because of obstacle, sound wave is reflected back towards source
With no change in speed of propagation
Angles of the reflected rays to the perpendicular equal angle of i
1. A 1000 Hz tone is presented at 50 dB. What is it in dB SPL?
2. A 250 Hz tone is presented at 60 dB HL. What is it in dB SPL?
60+ 25 = 85 dB SPL
3. A 1000 Hz tone is presented at 40 dB SPL. What is it on dB HL?
40 7 = 33 dB HL
Remember sine waves have one frequency
Complex sounds have more than one frequency
Will only include the odd harmonics of the fundamental
Gaussian Noise/White Noise
The Middle Ear
Middle ear muscles
Three tiny bones (Ossicles) transmit sound from the outer ear to the inner ears
Domes in contact with
Point of attachment is the Umbo
Range between the smallest intensity to detect a sound and the lrgest intensity
before damaging the ear.
Dynamic range is 10^15.
Change from an interval scale to a ratio scale:
Makes handling these numbers more manageable
Bel: unit of