# Complex sounds, decibels and psychoacoustics

 complex waves the sounds that we hear-they have a combination of many different frequencies each with its own amplitude and phase-can be periodic or aperiodic noise aperiodic sound that has random sound waves. -it can be transient (brief or short duration) or-it can be turbulent (continuous) Gaussian noise white noise-it should be flat when we measure it with equal energies across frequencies. used to calibrate a speaker or microphone sound takes place in time, frequency and intensity waveform a measure of amplitude by time. difficult to pick out specific frequencies spectrum good for showing specific frequencies and intensities but can not see changes over time fourier theorem any complex wave can be analyzed to determine the amplitude, frequency and phases of the sinusoidal components components of a complex wave fundamental frequency: lowest freq of a complex sound (not found in aperiodic sounds)harmonics:a whole number multiple of the fundamental freq ex fundamental is 100Hz it will contain harmonics of 200hz 300hz etc. but each may have different amplitudes resonance as things become more stiff or less massive they resonant at a higher frequency. the resonance frequencies is its favourite vibrating frequencies due to mass and stiffness stiffness vs mass stiffness opposes low Hz vibrations (ossicle ossification)mass opposes high Hz vibrations (ear infection)as we go up in stiffness resonance goes upas we go up in mass we go down in resonance frequency Sound pressure Level (dB SPL) looks at what is received on a diaphragm-measured in upa, 20upa smallest pressure required for a human with normal hearing to hear 1000Hz tone absolute equation changes upa to dB SPL20Xlog(p1/pref) pref=20 relative equation 20 X log(p1/p2)comparing two different pressure values psychoacoustics the study of the relationship between physical stimuli and psychological responsemeasures sound by pitch loudness and localization pitch describes how high or low a sound is perceived. In general is rises as Hz rises loudness subjective experience associated with sound pressure (amplitude) equal loudness contours in order for a sound to be perceived as louder you need to increase the intensity. In order for people to perceive different freq as the same established anchor or reference tone you need to increase the intensity. more for lower freq Localization the ability to determine where sound is coming from.-our ears use intensity and phase differences to determine location.High freq- intensity cueslow freq- phase cues AuthorWesleypjones ID316353 Card SetComplex sounds, decibels and psychoacoustics DescriptionComplex sounds, decibels and psychoacoustics Updated2016-02-23T04:39:55Z Show Answers