Page 52 - Spring 2006

Standards News
WHEN STANDARDS AND CLINICAL PRACTICE COLLIDE
Robert F. Burkard
Center for Hearing and Deafness, University of Buffalo Buffalo, New York 14214
In Accredited Standards Committee S3,
Bioacoustics, standards impact clinical
practice. In some cases, clinical practice
and standards development work synergis-
tically, whereas in other instances they are
antagonistic processes. The current scope
of S3 includes: “Standards, specifications,
methods of measurement and test, and ter-
minology in the fields of psychological and
physiological acoustics, including aspects
of general acoustics which pertain to bio-
logical safety, tolerance and comfort.” It
does not, however, allow us to dictate clinical practice. Many
of the S3 standards are relevant to the discipline of clinical
audiology. For example, ANSI S3.61 describes details about
the technical specifications and calibration of clinical
audiometers. As virtually all audiology clinics in the United
States have audiometers that are manufactured and calibrat-
ed to meet ANSI S3.6, this is clearly an important standard
related to the clinical measurement of hearing. As such, it is
relevant to the field of clinical audiology. It does not, howev-
er, dictate clinical practice. ANSI S3.6 does not tell the clini-
cian how to perform clinical tests, nor does it tell the clinician
how to interpret the results of these clinical tests. In this case,
the standards process is complementary to clinical practice.
A standard that does cross over the line into clinical practice
is ANSI S3.21 American National Standard Method for
2
In this standard, a common procedure for determining audiometric threshold is described. This is similar to the procedure recommended in most audiology textbooks for obtaining audiometric threshold. This standard clearly crosses over into the domain of clinical practice, and yet this standard has not been con- troversial. In this instance, the standard dictates a procedure that is used to obtain threshold in many clinical venues. It does not dictate when to use this procedure, nor does it tell the user how to interpret the results clinically. Perhaps this is why this standard has been around for a while (since 1978),
Manual Pure-Tone Threshold Audiometry.
and why it has not been problematic.
ANSI S3.453 describes the protocol used for testing
vestibular function. The development of this standard was contentious, and remains somewhat controversial. Several aspects of the standard were fiercely debated while it was under development. First, the adequate bandwidth for record- ing eye movements was debated. The standard states that for digital devices, the electrical potential measured when the eye moves should be sampled at no less than 100 Hz (giving a bandwidth of ~50 Hz). This specification was controversial, as at the time the standard was being developed, several com- mercially available systems digitized at a lower rate. This issue
“In some cases, clinical practice and standards development work synergistically, whereas in other instances they are antagonistic processes.”
was complicated by the fact that there was no clear literature that dictated this mini- mum sampling frequency to resolve the slow phase of eye movements. This specifi- cation could have potentially led to a serious conflict between the opinions of experts in the field (including those in the working group that was developing this standard) and the manufacturing community. The resolution to this potential conflict involved a grandfather clause, giving the manufac- turers five years until the revision of this
standard to meet this minimum digitization rate. This issue did not directly impact clinical practice, but did affect which instrumentation met the minimum requirements of the stan- dard. Another contentious issue surrounding this standard does actually get closer to the clinical practice line. For the clinical subtest of caloric testing, the temperature of the inner ear is changed, and the resulting eye movements (nystagmus) are recorded. In the literature, both water and air have been used to produce this temperature change. If one looks at the clinical literature, there are champions for the use of both air and water. There are those who argue that air is problematic unless air temperature is monitored at the tip of the probe that is placed in the ear canal. Others believe that air produces a less robust response, and for that reason its use should be dis- couraged. To summarize the clinical literature, there is no clear agreement as to whether the use of air for calorics is a good or bad clinical practice. Now let us see how this lack of clinical agreement on the use of air calorics affected the devel- opment and approval of this standard. At least a subset of the members of the working group developing this standard fell in the “don’t like air calorics” camp. One important principle of standards development is the notion of consensus. As the members of the working group could not agree that the use of air calorics was good clinical practice, the use of air calorics was not included in the standard. This omission might be interpreted as the standard dictating clinical practice. This actually is true, as you cannot follow the ANSI Standard and use air calorics, due to the omission. On the other hand, it is common to leave out controversial issues in a standard, issues on which consensus cannot currently be developed, in order to get the positive vote (consensus) needed to approve the stan- dard. In this particular instance, the worlds of clinical practice and standards development collided. From numerous phone calls and emails made to the S3 Chair (me) near the time this standard was approved, it is clear that a lot of people disagree with leaving air calorics out of the standard.
I write this brief article to point out that while it is not the charge of Accredited Standards Committee S3 to dictate clini-
50 Acoustics Today, April 2006