Editing Frequency modulation (section)

===Hearing assistive technology===
Frequency modulated systems are a widespread and commercially available [[assistive technology]] that make speech more understandable by improving the signal-to-noise ratio in the user's ear. They are also called ''auditory trainers'', a term which refers to any sound amplification system not classified as a [[hearing aid]]. They intensify signal levels from the source by 15 to 20 decibels.<ref>{{cite tech report |author=ASHA Ad Hoc Committee on FM Systems |date=2002 |orig-date=Original March 1994 |edition=Revised |title=Guidelines for Fitting and Monitoring FM Systems |institution=[[American Speech–Language–Hearing Association]] |url=https://www.asha.org/policy/gl2002-00010/ |doi=10.1044/policy.GL2002-00010}}</ref> FM systems are used by hearing-impaired people as well as children whose listening is affected by disorders such as [[auditory processing disorder]] or [[ADHD]].<ref>{{Cite journal |last1=Schafer |first1=Erin C. |last2=Bryant |first2=Danielle |last3=Sanders |first3=Katie |last4=Baldus |first4=Nicole |last5=Algier |first5=Katherine |last6=Lewis |first6=Audrey |last7=Traber |first7=Jordan |last8=Layden |first8=Paige |last9=Amin |first9=Aneeqa |date=June 1, 2014 |title=Fitting and Verification of Frequency Modulation on Children with Normal Hearing |journal=Journal of the American Academy of Audiology |volume=25 |issue=6 |pages=529–540 |doi=10.3766/jaaa.25.6.3 |issn=1050-0545 |pmid=25313543 |id={{EBSCOhost|107832936}} |via=[[EBSCOhost]]}}</ref> For people with [[sensorineural hearing loss]], FM systems result in better speech perception than hearing aids. They can be coupled with behind-the-ear hearing aids to allow the user to alternate the setting.<ref>{{Cite journal |last1=Lewis |first1=M. Samantha |last2=Crandall |first2=Carl C. |last3=Valente |first3=Michael |last4=Enrietto Horn |first4=Jane |date=2004 |title=Speech perception in noise: directional microphones versus frequency modulation (FM) systems |url=https://digitalcommons.wustl.edu/audio_hapubs/5 |journal=Journal of the American Academy of Audiology |volume=15 |issue=6 |pages=426–439 |doi=10.3766/jaaa.15.6.4 |pmid=15341224 |doi-access=free|url-access=subscription }}</ref> FM systems are more convenient and cost-effective than alternatives such as [[cochlear implants]], but many users use FM systems infrequently due to their conspicuousness and need for recharging.<ref>{{Cite journal |last=McArdle |first=Rachel |last2=Abrams |first2=Harvey B. |last3=Hnath Chisholm |first3=Theresa |date=2005 |title=When Hearing Aids Go Bad: An FM Success Story |journal=Journal of the American Academy of Audiology |volume=16 |issue=10 |pages=809–821 |doi=10.3766/jaaa.16.10.5 |id={{EBSCOhost|106441304}} |via=[[EBSCOhost]]}}</ref>