Lecture program Psychoacoustics and instrumentation

1. PSYCHOACOUSTICS
OF DISCRIMINATING AND
IDENTIFYING SOUNDS

2. Psychoacoustics:
■ Psychoacoustics is essentially the study of the
perception of sound and includes:
– How we listen,
– Our psychological responses,
– And the physiological impact of music and sound
on the human nervous system.
■ Traditionally, psychoacoustics is broadly defined as "pertaining
to the perception of sound and the production of speech."

3. ■ The study of psychoacoustics dissects the listening
experience.
– In psychoacoustics, the terms music, sound,
frequency, and vibration are interchangeable,
because they are different approximations of the
same essence.

4. ■ An important distinction is the difference between a
psychological and a neurological perception.
– A song or melody associated with childhood, a teenage
romance, or some peak emotional experience creates a
memory-based psychological reaction.
– There is also a physiological response to sounds
■ Slightly detuned tones can cause brain waves to speed up or slow
down, for instance.

5. ■ Additionally, soundtracks that are filtered and gated
(this is a sophisticated engineering process) create a
random sonic event. It triggers an active listening
response and thus tonifies the auditory mechanism,
including the tiny muscles of the middle ear.
■ As a result, sounds are perceived more accurately, and
speech and communication skills improve.

6. How does noise talk to us?
a) Noise is informative, that means it gives the listener
information about quality, functionality, danger and other
environment.
b) Noise implies a certain image of the product, maybe
luxury, sportive, dangerous and so on.
c) Noise may identify the product similar to the optical
impression. That means a corporate sound of a product fits to
the expectation to the listener.

7. What kind of tasks are related to the
psychoacoustics?
a) The description of the perception of sound events. how does
the hearing perceive sound, what kind of analysis we
should use comparable to the human inner-ear and what
kind of signal processing and sound evaluation are be done
by the human hearing?
b) To get an objective description of subjective perceived
sound quality.
c) Describe the transformation of a sound event into a
hearing event.

8. ■ Psychoacoustics has become an invaluable tool in designing
hearing aids and cochlear implants, and in the study of hearing
generally.
■ “Psychoacoustics is fundamental,” “You need to know how the
normally functioning auditory system works — how sound
relates to human perception.”

9. ■ The field’s origin dates back more than a century, to the first
efforts to quantify the psychological properties of sound. What
tones could humans hear, and how loudly or softly did they need
to be heard?
■ Pitch could be measured in hertz and loudness in decibels, but
other phenomena were not so easily quantified.

10. ■ Human hearing can discern the movement of sound with a
surprising degree of accuracy
■ It can distinguish timbre, the difference between a clarinet and
a saxophone.
■ It can remember patterns of speech, to immediately identify a
friend in a phone call years after last hearing the voice.
■ And a parent can effortlessly sift the sound of an infant’s cry
from the blare of a televised football game.

11. ■ Finally there were the imponderables, things we do with our
hearing simply because we can.
– “Everyone knows the sound of a bowling ball as it rolls
down the alley,”
– “What is it about that sound that we can identify?”

12. ■ For much of the 20th century, engineers devoted themselves to
developing acoustical hardware like amplifiers, speakers and
recording systems.
■ After World War II, scientists learned how to use mathematical
formulas to “subtract” unwanted noise from sound signals.
■ Then they learned how to make sound signals without any
unwanted noise.
■ Next came stereo. By recording two tracks, engineers could
localize sound for the listener. “If something’s louder on one
side, you’ll hear it on that side.”

13. ■ But stereo had no real psychoacoustics.
– It created an artificial sense of space with a second track,
but did so by dealing with only one variable — loudness
– And enhanced human perception simply by suggesting that
listeners separate their speakers.

14. ■ The digital age changed all this, allowing engineers to
– Manipulate sound in ways that had never been tried before.
– They could create sounds that had never existed,
– eliminate sounds they did not want and
– use constant changes in filter combinations to deliver sound
to listeners with a fidelity that had never before been
possible.

15. ■ Digital technology has led to innovations that have been critical
– in improving sound reproduction,
– in tailoring hearing aids for individual patients and
– in treating hearing impairment and developing cochlear
implants
■ “Hearing aids are not the same as glasses,”
■ “It’s never been just about hearing sound; it’s also about
understanding sound and separating it from background noise.
– This happened with microprocessors.
– Without them it would have been impossible.”

16. ■ Psychoacoustics has shown engineers that they still have a long
way to go.
– No machine can yet duplicate the ability of the human ear
to understand a conversation in a crowded restaurant.
■ People with cochlear implants have
– “a terrible time” with background noise.
– They also have trouble with pitch perception and
distinguishing the sounds of different instruments. “