Intensity is a measure of _________.
The amplitude of the signal can be easily _____ _____.
What is the challenge of measuring the microphone signal of a person's voice?
the signal goes up and down in it's amplitude all the time so it is constantly changing.
What is RMS?
root mean square
What does RMS represent?
the amplitude of the signal
How does RMS work?
1st: take all of the values + and - of the signal and square them
2nd: get the average of the squared values (it will be +)
3rd: get the square root of the average which then gives you the RMS
What can RMS be applied to?
number of harmonic components
What is acoustic power?
*how much energy is radiated
*it is measured in watts
*represents the amount of energy transfer in a given amount of time
What does WATTS represent?
the amount of energy that can be transferred by the system
*in the case of a music system, the energy comes from a battery or from the electrical wall socket and the output from this system is acoustic energy
What does a transducer do?
converts electrical energy into acoustic energy
*a home stereo is a transducer
How is intensity defined?
WATTS divided by a unit area
*if you take the amount of energy that a stereo is giving out and divide it across the surface of a sphere you see that there's less energy availabe per unit area as that sphere gets larger
*it is simply spread out over a larger surface
What happens as the radius gets bigger?
the intensity drops not in proportion to the distance but in proportion to the square of the distance
What is the inverse square law?
describes how sound diminishes as the distance from the sound source increases
What is the general principle of the inverse square law?
to specify exactly how the intensity of sound diminishes as the hearer/recorder gets further away form the speaker/sound source
The inverse square law has important implications for what?
measuring sound pressure level in decibels of a person's spoken output because the distance of our measuring device from the speaker makes an enormous difference to the actual decibel values that we measure
What is the benefit of a logarithimic scale?
it is capable of accomodating a large range of numbers in a very straight forward and visually intuitive way
Why do we use logarithimic numbers and decibels?
because values in watts are too cumbersome
Decibels are a logarithmic measure of what?
What is the great value in using a decibel scale?
it allows us to span a wide range of intensitites using numbers that aren't absolutely enormous or totally minuscule.
What type of characteristic is loudness and what does it correlate to?
a perceptual characteristic
How is loudness judged?
by the human listener
cannot be measured by equipment
What does assembling a psycho physical scale mean?
making a connection between somebody's perceptual response or experience to a physical measure that links the two parameters together
Loudness is influenced by what?
frequency and spectrum
What complicates our perception of loudness?
Our hearing is not equally sensitive to all frequencies; it is heavily influenced by the frequency that we are listening to
What range do our ears have the greatest sensitivity to sounds?
the middle range around 1000 Hz
At which range do our ears have substantially less sensitivity to sound?
very low frequencies and very high frequencies
What does a sound level meter do?
measures intensity in decibels
How do you use a sound level meter in the clinic?
as a biofeedback tool; measure clients speech intensity while they're talking and then give them feedback that will help them aim for a particular target (higher or lower depending on their need)
There are some things to keep in mind when using a sound meter level. They are:
*distance is crucial: it must be known or at least kept constant from one session to another because of the inverse square law
*keep mouth to mic distance constant
*keep input settings constant for each session
When doing research and publishing it is important to state these 2 things.
*that they used dB SPL
*the distance of the sound level meter from the speaker
In the clinic what measurments are ok to use?
relative measures as long as you're comparing like with like
What happens when we adjust the loudness of our speech?
*increase our subglottal pressure/more driving pressure for loud speech
*it causes the vocal folds to move farther apart as they oscillate = more forceful vocal fold collisions
*larger articulator movements
*because more pressure has come from the lungs to drive the larynx, there is higher oral presure as you form consonants thus, the consonant burst release is stronger
Explain why the articulators would move more for louder speech.
the pressure within the oral cavity is much higher so you would need more forceful closure of the lips for a bilabial stop because if you increased the pressure and didn't increase the lip closure force, you would end up leaking air when you really wanted to have good stop closure
What is a VRP and what does it do?
Voice Range Profile: measures dynamic range; from lowest to highest intensity across a person's (dB range) Fo range
Data collected from the VRP can tell us what?
*overall capacity of a person's voice
*the shape and dimensions of VRP will vary across individuals and within individuals before and after treatment
Why does minimum amplitude level in decibels get higher as you go left to right to the higher Fo's?
Fo increases tend to be associated with amplitude increases due to physiological reasons
What are the physiological reasons Fo increases tend to be associated with amplitude increases?
if you are going to sustain a very high note at a very high Fo it means that you need to activate the cricothyroid muscle to stretch the vocal folds substantially; the vocal folds would be quite stiff and in order to get them to vibrate when they are that stiff you need to apply greater pressure and this will result in higher amplitude phonation simply because it is difficult to get the vocal folds to oscillate when they are stiff; you have to drive them much harder to do so as you drive them harder it's then impossible to sustain a very soft input
Ideas to keep in mind when using VRP in practice are:
*somewhat time consuming to collect all the data points
*useful for voice disordered patients
*practice helps them become better
*motivation plays a role
*max effort can vary with instructions
*be careful to avoid risk of vocal damage