Haas Effect Also called the precedence
effect, describes the human psychoacoustic phenomena for identifying
the direction of a sound source heard from two directions but
arriving at different times. Due to the head's geometry (two ears
spaced apart, separated by a barrier) the direct sound from any
source first enters the ear closest to the source, then the ear
farthest away. The brain uses the time difference between these
two arrivals to determine the direction in the horizontal plane
of the sound source (localization in the vertical plane relies
on subtle clues from the folds in the human ear).
Sound arriving at both ears simultaneously is heard as
coming from straight ahead, or behind, or within the head.
The Haas Effect tells us that humans localize a sound source
based upon the timing clues in the sound arriving over the first
few Milliseconds of an acoustical event. If subsequent arrivals
from different locations are within 10-35 milliseconds of the
first, the later arrivals are integrated with and perceived as
arriving form the location of the first arrival.
If the second arrival is longer than 35 milliseconds two
distinct sounds (the original and a echo) are heard. The Haas Effect is occurs even when the
second arrival is louder than the first (even by as much as 10
dB!). In essence we do not "hear" the delayed sound.
(See Helmut Haas's doctorate dissertation
presented to the University
"Über den Einfluss
eines Einfachechos auf die Hörsamkeit von Sprache;" translated
into English by Dr. Ing. K.P.R. Ehrenberg,
Building Research Station, Watford, Herts.,
England Library Communication no. 363, December, 1949; reproduced
in the United States as "The Influence of a Single Echo on
the Audibility of Speech," J. Audio Eng. Soc., Vol.
20 (Mar. 1972), pp. 145-159.)
half-duplex Pertaining to a transmission over
a circuit capable of transmitting in either direction, but only
one direction at a time. See also: duplex
harmonic series 1.
Mathematics. A series whose terms are
in harmonic progression, as 1 + 1/3 + 1/5 + 1/7 + . . . 2.
Music. A series of tones consisting of
a fundamental tone and the overtones produced by it, and whose
frequencies are consecutive integral multiples of the frequency
of the fundamental.
handshaking The initial
exchange between two communications systems prior to and during
transmission to ensure proper data transfer.
hard disk A sealed mass
storage unit used for storing large amounts of digital data.
hard disk recording (HDR)
See: DAW (digital audio workstation)
hardware The physical
(mechanical, and electrical) devices that form a system. Separate
and distinct from the software code or the program material.
(high density compact disc) See: DVD
HDCD (high definition compatible digital) Pacific Microsonics'
trademark for their encode/decode scheme that allows up to 24
bit, 88.2 kHz digital audio mastering process, yet is compatible
with normal 16 bit, 44.1 kHz CD and DAT formats. Claimed to sound superior
even when not decoded, and to be indistinguishable from the original
HDTV (high definition television)
The standard for digital television in North America,
still being revised.
Helmholtz, Hermann Ludwig Ferdinand von
(1821-1894) German physicist and physiologist who formulated the
mathematical law of the conservation of energy (1847) and invented
an ophthalmoscope (1851) [An instrument for examining the interior
structures of the eye, especially the retina, consisting essentially
of a mirror that reflects light into the eye and a central hole
through which the eye is examined. You aren't a real doctor without
one!] Famous for his book, On the Sensations of Tone first
published in 1862.
hertz Abbr. Hz.
A unit of frequency equal to one cycle per second. [After
Heinrich Rudolf Hertz.]
Hertz, Heinrich Rudolf (1857-1894) German physicist
who was the first to produce radio waves artificially.
hexadecimal A number system using the base-16,
i.e., each number can be any of 16 values. Normally
represented by the digits 0-9, plus the alpha characters A-F.
Each hexadecimal digit can be represented by a four-bit binary
Hi8 See: DA-88
filter A filter having a passband
extending from some finite cutoff frequency (not zero) up to infinite
Holophonics An acoustical recording
and broadcast technology claimed to be the aural equivalent to
holography, hence the name. Holophonics
is an encode process that occurs during the recording session
using a special listening device named "Ringo."
It is claimed that "playback or broadcast is possible over
headphones or any existing mono or stereo speaker system, with
various levels of spatial effect. Optimal effects
occurs when two tracks (stereo) are played utilizing digital
technology over headphones."
HTML (hypertext markup language)
The software language used on the Internet's World Wide Web (WWW). Used
primarily to create web pages.
HTTP (hypertext transfer protocol) The
name for the protocol that moves documents around the Internet/Web.
Used by the various servers and browsers to communicate over the
hybrid A telecommunication term used to describe
an interface box that converts a conversation (or data signal)
coming in on two pairs (one pair for each direction of the conversation
or signal) onto one pair and vice versa (i.e., a 2-wire to 4-wire
converter). The name comes from the original use of a "hybrid
coil" in the telephone whose function was to keep the send
and receive signals separated. Both analog and digital hybrid
designs are used.
hyperlink The protocol
that allows connecting two Internet resources via a “link”; allowing
the user a simple point-and-click method to move from viewing
one resource to the next.
hypertext Within WWW documents,
the linking of words to other sections of text, pictures or sound
is called hypertext. Hypertext is created using the HTML