For further elaborations, please see Xu (2006a).
- Experimental control. It is often claimed that
so-called laboratory speech is unnatural and hence cannot be used to learn
about natural speech. However, without rigorous experimental control, one
can never be certain whether an observed pattern is a functional structure
of speech or a byproduct of several different mechanisms. As long as the
assumptions and claims of laboratory studies are properly made, the risk
of finding speech patterns that occur only in the laboratory but never in
natural conversation is much smaller than the risk of failing to find the
basic mechanisms by directly observing natural speech without proper experimental
control. Also, just as importantly, experimental control should not be equated
to laboratory/instrumental observation. The latter is only about the means
of observation, thus should not be taken as synonymous to experimental
- Always look for actual mechanisms. One of the ultimate
goals of science is to understand the world rather than to just describe
it. The same is true for speech science: it is not enough to simply describe
the phenomena we observe and give each a name; rather, it is more important
to understand the mechanisms that generate the observed phenomena. Furthermore,
whether we can discover the actual mechanisms depends much on whether we
are consciously and persistently looking for them. Naming ≠ understanding.
- Spare no details. Scientific understanding can
be only as accurate as the level of detail we choose to use in making
our observations. If one takes measurements from only a limited number
of points, such as peaks, valleys, the middle point, etc., in the speech
samples they study, although certain gross patterns can be observed, the
causal relations between the contributing factors and observed patterns is
difficult to establish. For this reason, as long as feasibility allows,
which itself should also be a goal for improvement, observations and measurements
should be as fine-grained as possible.
- One step at a time. To effectively tease apart
the tightly intertwined mechanisms of speech, it is critical to first
isolate the most tangible one, and then extend the understanding to the
less tangible ones. It is critical, however, that once a mechanism is
established, variations clearly due to it should not be re-attributed
to other mechanisms.
Goal of studying speech
production & perception
- To recognize all individual communicatively functional units
- To understand the mechanisms of their transmission.
for Recognizing Communicatively Functional Units
- They need to be concrete rather than symbolic or featural; otherwise
their execution would not be possible.
- They need to be distinct from each other in form, otherwise they
could not be recognized in perception.
- They need to be stable and remain relatively constant across
various conditions, otherwise their production and perception would both
Basic Criteria for Recognizing Transmission
For further elaborations, please see Xu (2006b).
- Speech is produced by a physical device — the articulatory system;
so it necessarily reflects the mechanical properties of the articulators.
- Speech production is controlled by the Central Nervous System
(CNS); so it necessarily bears the properties of CNS and the characteristics
of its interaction with the articulatory system.
- Speech is perceived by the auditory system of human listeners;
so it is necessarily constrained by the properties of the auditory system.