June 3rd 2024 – KTD Acoustics

This problem does not exist in most other branches of physical science, where there is only one correct adjective. Note that we refer to “physical” science but that it would be obviously incorrect to use “physic” science. In chemistry, we would use “chemical” references but not “chemic” ones. In general, we may speak of “scientific” findings, but never “scientifical” ones. In other fields, both the “-ic” and “-ical” adjectives exist, whereby in some cases the terms are essentially interchangeable, such as “anatomic” and “anatomical,” whereas for others, such as “economic” and “economical,” there are relatively clear and well-established distinctions in definition.

There is, however, another field of science that shares in our dilemma, and from which we can derive a sense of how to make the distinction. Interestingly, this is a field that, coincidentally or not, there are manifold analogies to, and shared terms with, the field of acoustics. This is, of course, the field of electricity, where both the “electric” and “electrical” adjectives are used. It therefore seems only appropriate that the same standard applied to electricity-related descriptors is applied to those of sound, not just because it is one, if not the only, other field in the physical sciences for which both the adjectival suffixes -ic and -ical are ubiquitous, but also since those suffixes will go on to modify the very same nouns in both fields – think about terms like “impedance,” “energy,” “conduit,” “power,” “engineer,” etc.

It seems relatively well established that electric and electrical have different applications. In summary, electric is used to modify terms that are closely related to the physical principles of electricity and the movement of electrons, while electrical is used for nouns more generally associated with the science of electricity. As examples, we would use electric for the terms current, potential, resistance, load, impedance, and charge, and electrical for the terms engineer, measurement, issue, and society.

By extension, and in accordance with Hunt’s (1955) proposed definition, acoustic should be used when the term being modified has the properties, dimensions, or physical characteristics associated with sound waves, while acoustical should be used when the term does not have such properties, dimensions, or physical characteristics. We could therefore test the acoustic absorptivity of a material by placing it in our acoustical testing apparatus, which consists of a tube to measure acoustic impedance, whereby the magnitude of incident and reflected acoustic waves is measured by an acoustical engineering student, who one day hopes to be part of a prestigious acoustical society.

Currently, the -ic and -ical suffixes are often used interchangeably in the field of acoustics. To paraphrase Hunt, the distinction between the terms can be deemed trivial, and therefore something that can simply be resolved on the basis of euphony, however, consistency is a handy thing in case of argument. I would extend this by saying consistency is not only handy, but necessary to preserve the integrity of language. It is not a matter of pedantry to insist that indiscriminate interchangeability between the terms would mean we have a useless redundancy in our language, and that there is compelling reason for a consistent distinction, even if not widely understood or implemented notwithstanding historical, published arguments for it.

So, are we acoustic consultants or acoustical consultants? In my view, it is resounding and unequivocal – we are acoustical consultants.