What is the difference between frequency compression and frequency transposition?
Answer
For the most part, we are talking about terminology differences: "Frequency Transposition" is a nontechnical, generic term to describe frequency lowering. Sonovation/AVR used this term in the early 1990's. The term Frequency Transposition was also used by others to describe instruments that used "Frequency Shifting" (another term that adds to the confusion). In an attempt to separate Sonovation/AVR's technology from the others, we started using the term Frequency Compression. Here are the main differences between "Frequency Shifting" and "Frequency Compression":
Frequency shifting is a technical term specifically relating to the use of a mixer (as in electric circuits not the kitchen appliance) to lower the signal by a fixed frequency value. The problem with shifting is that is does not reduce the bandwidth. It only shifts the signal down. This creates very strong distortions when the shifting frequency is greater than the signal frequency.
In comparison, Frequency Compression reduces both the frequency and the bandwidth by a preset ratio (factor). Because the spectrum is "squeezed" with Frequency Compression, operating in real-time requires a complex algorithm that maintains the critical information.
The graphics below demonstrate the differences.
Wendy Davis has been an audiologist for 15 years. She practiced as a clinical audiologist and educational audiologist for 6 years before joing Sonovation/AVR in 1994. Ms. Davis is involved in research and product development as well as training and clinical support for Sonovation/AVR. She can be reached at wedavis@avrsono.com.
Wendy Davis, MS
Related Courses
1https://www.audiologyonline.com/audiology-ceus/course/deeper-look-at-sound-environments-33536A Deeper Look at Sound EnvironmentsThe characteristics of the sound environment have a fundamental impact on the performance of the hearing aid user. In this course, we will describe the obvious and sometimes more subtle aspects of sound environments that will affect hearing aid performance.auditory, textual, visual
The characteristics of the sound environment have a fundamental impact on the performance of the hearing aid user. In this course, we will describe the obvious and sometimes more subtle aspects of sound environments that will affect hearing aid performance.
2https://www.audiologyonline.com/audiology-ceus/course/subjective-evaluation-new-hearing-aid-35584The Subjective Evaluation of a New Hearing Aid FittingThe final judge of the success of a new fitting will of course be the patient, and the criteria that they use may not always be in line with an objective audiological measure. This course will review some of the issues and options at play when having the patient weigh in on the value of the new devices.auditory, textual, visual
'Very informative and pragmatic presentation regarding the importance of incorporating a subjective evaluation into the hearing aid fitting process'Read Reviews
The final judge of the success of a new fitting will of course be the patient, and the criteria that they use may not always be in line with an objective audiological measure. This course will review some of the issues and options at play when having the patient weigh in on the value of the new devices.
3https://www.audiologyonline.com/audiology-ceus/course/auditory-wellness-what-clinicians-need-36608Auditory Wellness: What Clinicians Need to KnowAs most hearing care professionals know, the functional capabilities of individuals with hearing loss are defined by more than the audiogram. Many of these functional capabilities fall under the rubric, auditory wellness. This podcast will be a discussion between Brian Taylor of Signia and his guest, Barbara Weinstein, professor of audiology at City University of New York. They will outline the concept of auditory wellness, how it can be measured clinically and how properly fitted hearing aids have the potential to improve auditory wellness.auditory
As most hearing care professionals know, the functional capabilities of individuals with hearing loss are defined by more than the audiogram. Many of these functional capabilities fall under the rubric, auditory wellness. This podcast will be a discussion between Brian Taylor of Signia and his guest, Barbara Weinstein, professor of audiology at City University of New York. They will outline the concept of auditory wellness, how it can be measured clinically and how properly fitted hearing aids have the potential to improve auditory wellness.
4https://www.audiologyonline.com/audiology-ceus/course/vanderbilt-audiology-journal-club-clinical-37376Vanderbilt Audiology Journal Club: Clinical Insights from Recent Hearing Aid ResearchThis course will review new key journal articles on hearing aid technology and provide clinical implications for practicing audiologists.auditory, textual, visual
5https://www.audiologyonline.com/audiology-ceus/course/61-better-hearing-in-noise-3865661% Better Hearing in Noise: The Roger PortfolioEvery patient wants to hear better in noise, whether it be celebrating over dinner with a group of friends or on a date with your significant other. Roger technology provides a significant improvement over normal-hearing ears, hearing aids, and cochlear implants to deliver excellent speech understanding.auditory, textual, visual
Every patient wants to hear better in noise, whether it be celebrating over dinner with a group of friends or on a date with your significant other. Roger technology provides a significant improvement over normal-hearing ears, hearing aids, and cochlear implants to deliver excellent speech understanding.
