Editing Stethoscope (section)

==Types==

===Acoustic===
[[File:Stethoscope.svg|thumb|Parts of a binaural stethoscope]]
[[Image:Stethoscope pink.JPG|thumb|150px|right|Acoustic stethoscope, with the ''bell'' upwards]]

Acoustic stethoscopes operate on the transmission of sound from the chest piece, via air-filled hollow tubes, to the listener's ears. The chestpiece usually consists of two sides that can be placed against the patient for sensing sound: a diaphragm (plastic disc) or bell (hollow cup). If the diaphragm is placed on the patient, body sounds vibrate the diaphragm, creating acoustic pressure waves which travel up the tubing to the listener's ears. If the bell is placed on the patient, the vibrations of the skin directly produce acoustic pressure waves traveling up to the listener's ears. The bell transmits low frequency sounds, while the diaphragm transmits higher frequency sounds. To deliver the acoustic energy primarily to either the bell or diaphragm, the tube connecting into the chamber between bell and diaphragm is open on only one side and can rotate.  The opening is visible when connected into the bell. Rotating the tube 180 degrees in the head connects it to the diaphragm. This two-sided stethoscope was invented by Rappaport and Sprague in the early part of the 20th century.{{citation needed|date=June 2019}}

===Electronic{{anchor|Digital Stethoscope|Electronic Stethoschope}}===
[[File:Electronic stethoscope.jpg|thumb|Electronic stethoscope]]An electronic stethoscope (or '''stethophone''') overcomes the low sound levels by electronically amplifying body sounds. However, amplification of stethoscope contact artifacts, and component cutoffs (frequency response thresholds of electronic stethoscope microphones, pre-amps, amps, and speakers) limit electronically amplified stethoscopes' overall utility by amplifying mid-range sounds, while simultaneously attenuating high- and low- frequency range sounds. Currently, a number of companies offer electronic stethoscopes. Electronic stethoscopes require conversion of acoustic sound waves to electrical signals which can then be amplified and processed for optimal listening. Unlike acoustic stethoscopes, which are all based on the same physics, transducers in electronic stethoscopes vary widely. The simplest and least effective method of sound detection is achieved by placing a microphone in the chestpiece. This method suffers from ambient noise interference and has fallen out of favor. Another method, used in Welch-Allyn's Meditron stethoscope, comprises placement of a piezoelectric crystal at the head of a metal shaft, the bottom of the shaft making contact with a diaphragm. 3M also uses a piezo-electric crystal placed within foam behind a thick rubber-like diaphragm. The Thinklabs' Rhythm 32  uses an [[electromagnetic diaphragm]] with a conductive inner surface to form a capacitive sensor. This diaphragm responds to sound waves, with changes in an electric field replacing changes in air pressure.  The Eko Core enables wireless transmission of heart sounds to a smartphone or tablet. The Eko Duo can take [[Electrocardiography|electrocardiograms]] as well as echocardiograms. This enables clinicians to screen for conditions such as [[heart failure]], which would not be possible with a traditional stethoscope.<ref>{{Cite journal |title=Smart stethoscope uses artificial intelligence to screen for heart failure |url=https://evidence.nihr.ac.uk/alert/smart-stethoscope-artificial-intelligence-screen-heart-failure/ |journal=NIHR Evidence|date=18 January 2023 |doi=10.3310/nihrevidence_56245 |s2cid=257852883 }}</ref><ref>{{Cite journal |last1=Bachtiger |first1=Patrik |last2=Petri |first2=Camille F |last3=Scott |first3=Francesca E |last4=Ri Park |first4=Se |last5=Kelshiker |first5=Mihir A |last6=Sahemey |first6=Harpreet K |last7=Dumea |first7=Bianca |last8=Alquero |first8=Regine |last9=Padam |first9=Pritpal S |last10=Hatrick |first10=Isobel R |last11=Ali |first11=Alfa |last12=Ribeiro |first12=Maria |last13=Cheung |first13=Wing-See |last14=Bual |first14=Nina |last15=Rana |first15=Bushra |date=2022-02-01 |title=Point-of-care screening for heart failure with reduced ejection fraction using artificial intelligence during ECG-enabled stethoscope examination in London, UK: a prospective, observational, multicentre study |journal=The Lancet Digital Health |language=en |volume=4 |issue=2 |pages=e117–e125 |doi=10.1016/S2589-7500(21)00256-9 |pmc=8789562 |pmid=34998740}}</ref> 

Because the sounds are transmitted electronically, an electronic stethoscope can be a [[wireless]] device, can be a recording device, and can provide noise reduction, signal enhancement, and both visual and audio output. Around 2001, Stethographics introduced PC-based software which enabled a phonocardiograph, graphic representation of cardiologic and pulmonologic sounds to be generated, and interpreted according to related algorithms. All of these features are helpful for purposes of [[telemedicine]] (remote diagnosis) and teaching.{{citation needed|date=May 2023}}

Electronic stethoscopes are also used with [[Computer-aided Auscultation|computer-aided auscultation]] programs to analyze the recorded heart sounds pathological or innocent heart murmurs.

====Recording====

Some electronic stethoscopes feature direct audio output that can be used with an external recording device, such as a [[notebook computer|laptop]] or [[MP3]] recorder. The same connection can be used to listen to the previously recorded [[auscultation]] through the stethoscope headphones, allowing for more detailed study for general research as well as evaluation and consultation regarding a particular patient's condition and [[telemedicine]], or remote diagnosis.<ref>Palaniappan R, Sundaraj K, Ahamed NU, Arjunan A, Sundaraj S. Computer-based Respiratory Sound Analysis: A Systematic Review. IETE Tech Rev 2013;30:248–56</ref>

There are some [[smartphone]] apps that can use the phone as a stethoscope.<ref>Bianca K. Chung, Brad Tritle, "The power of mobile devices and patient engagement", [https://books.google.com/books?id=7YMsAgAAQBAJ&pg=PA93 p. 93], chapter 8 in Jan Oldenburg (ed), ''Engage! Transforming Healthcare Through Digital Patient Engagement'', Himss Books, 2012 {{ISBN|1938904397}}.</ref>  At least one uses the phone's own microphone to amplify sound, produce a visualization, and e-mail the results.  These apps may be used for training purposes or as novelties, but have not yet gained acceptance for professional medical use.<ref>William Hanson, ''Smart Medicine: How the Changing Role of Doctors Will Revolutionize Health Care'', [https://books.google.com/books?id=FKlKjUgduP0C&pg=PA22 pp. 20–22], Macmillan, 2011 {{ISBN|0230120938}}.</ref>

The first stethoscope that could work with a smartphone application was introduced in 2015  <ref>Matt McFarland, "Eko's stethoscope shows the potential of digital technology to reinvent health care", [https://www.washingtonpost.com/news/innovations/wp/2015/09/02/ekos-stethoscope-shows-the-potential-of-digital-technology-to-reinvent-health-care/], Washington Post</ref>

===Fetal===
[[File:Pinard horn Uganda US Army nurse.jpg|150px|right|thumb|A [[Pinard horn]] used by a U.S. Army Reserve nurse in Uganda]]
{{main|Pinard horn}}

A ''fetal stethoscope'' or ''fetoscope'' is an acoustic stethoscope shaped like a listening trumpet. It is placed against the [[abdomen]] of a [[pregnancy|pregnant]] woman to listen to the heart sounds of the [[fetus]].<ref>{{cite book|author=Arup Kumar Majhi|title=Bedside Clinics In Obstetrics|url=https://books.google.com/books?id=-7zfDAAAQBAJ&pg=PA47|date=2016-08-16|publisher=Academic Publishers|isbn=978-93-83420-87-2|pages=47–}}</ref> The fetal stethoscope is also known as a [[Pinard horn]] after French [[obstetrician]] [[Adolphe Pinard]] (1844–1934).

===Doppler===

A Doppler stethoscope is an electronic device that measures the [[Doppler effect]] of [[ultrasound]] waves reflected from organs within the body.  Motion is detected by the change in frequency, due to the Doppler effect, of the reflected waves.  Hence the Doppler stethoscope is particularly suited to deal with moving objects such as a beating heart.<ref>S. Ananthi, ''A Textbook of Medical Instruments'', pp. 290–96, New Age International, 2006 {{ISBN|8122415725}}.</ref>
It was recently demonstrated that continuous Doppler enables the auscultation of valvular movements and blood flow sounds that are undetected during cardiac examination with a stethoscope in adults. The Doppler auscultation presented a sensitivity of 84% for the detection of aortic regurgitations while classic stethoscope auscultation presented a sensitivity of 58%. Moreover, Doppler auscultation was superior in the detection of impaired ventricular relaxation. Since the physics of Doppler auscultation and classic auscultation are different, it has been suggested that both methods could complement each other.<ref>Mc Loughlin MJ and Mc Loughlin S. Cardiac auscultation: Preliminary findings of a pilot study using continuous Wave Doppler and comparison with classic auscultation Int J Cardiol. 2013 Jul 31; 167(2):5 90–91</ref><ref>{{cite book|url=https://www.amazon.com/Cardiac-Auscultation-Continuous-Stethoscope-ebook/dp/B00AXFB2IG/|title=Amazon.com: Cardiac Auscultation With Continuous Wave Doppler Stethoscope: A new method 200 years after Laennec's invention eBook: Mario Jorge Mc Loughlin, Santiago Mc Loughlin: Kindle Store|date=5 January 2013|publisher=Mario J Mc Loughlin |access-date=24 September 2015}}</ref>
A military noise-immune Doppler based stethoscope has recently been developed for auscultation of patients in loud sound environments (up to 110&nbsp;dB).

===3D-printed===
[[File:StethoscopebyTarek.jpg|thumb|A 3D-printed stethoscope]]
A '''3D-printed stethoscope''' is an open-source medical device meant for [[auscultation]] and manufactured via means of [[3D printing]].<ref>[https://github.com/GliaX/Stethoscope Official project site] at GitHub</ref> The 3D stethoscope was developed by Dr. Tarek Loubani and a team of medical and technology specialists. The 3D-stethoscope was developed as part of the Glia project, and its design is open source from the outset. The stethoscope gained widespread media coverage in Summer 2015.

The need for a 3D-stethoscope was borne out of a lack of stethoscopes and other vital medical equipment because of the [[blockade of the Gaza Strip]], where Loubani, a Palestinian-Canadian, worked as an emergency physician during [[Operation Pillar of Defense|the 2012 conflict in Gaza]]. The 1960s-era ''[[David Littmann|Littmann Cardiology 3]]'' stethoscope  became the basis for the 3D-printed stethoscope developed by Loubani.<ref name="TheRegister">{{cite web |last=Pauli |first=Darren |title=Gazan medico team 3D-prints world-leading stethoscope for 30c |website=The Register |location=United Kingdom |date=2015-08-14 |url=https://www.theregister.co.uk/2015/08/14/printed_stethoscope_cccamp/ |access-date=2015-08-17}}</ref>

===Esophageal===
Prior to the 1960s, the esophageal stethoscope was a part of the routine intraoperative monitoring.<ref name="Brodsky2007">{{cite journal |last1=Brodsky |first1=J |last2=Lemmens |first2=H |title=The history of anesthesia for thoracic surgery |journal=Minerva Anestesiologica |volume=73 |issue=10 |pages=513–24 |date=2007 |pmid=17380101 }}</ref>