Please distinguish between „sounding“ (Loten) and echo sounding (Echoloten). The latter technique uses transducer to emit and to receive echos.

Das Lot in der Schifffahrt ist ein Gerät zur Messung der Wassertiefe. Das klassische Handlot besteht aus einer Lotleine und einem Gewicht an deren Ende. Das moderne Echolot misst die Tiefe elektronisch mittels Schallwellen. Das Lot dient zur Vermessung der Wassertiefen, zur Schiffssicherheit und zum Aufspüren von Fischschwärmen.
https://de.wikipedia.org/wiki/Lot_(Schifffahrt)

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Depth sounding refers to the act of measuring depth. It is often referred to simply as sounding. Data taken from soundings are used in bathymetry to make maps of the floor of a body of water, and were traditionally shown on nautical charts in fathoms and feet. The National Oceanic and Atmospheric Administration (NOAA), the agency responsible for bathymetric data in the United States, still uses fathoms and feet on nautical charts. In other countries, the International System of Units (metres) has become the standard for measuring depth.
"Sounding" derives from the Old English sund, meaning swimming, water, sea; it is not related to the word sound in the sense of noise or tones
https://en.wikipedia.org/wiki/Depth_sounding

Das Echolot ist ein in der Schifffahrt verwendetes Gerät zur elektroakustischen Messung von Wassertiefen (Lotung). Gemessen wird die Zeit, die zwischen der Aussendung eines Schallimpulses (Wasserschall) und der Ankunft der vom Gewässerboden reflektierten Schallwellen verstreicht.
https://de.wikipedia.org/wiki/Echolot

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Echo sounding is a type of SONAR used to determine the depth of water by transmitting sound pulses into water. The time interval between emission and return of a pulse is recorded, which is used to determine the depth of water along with the speed of sound in water at the time. This information is then typically used for navigation purposes or in order to obtain depths for charting purposes. Echo sounding can also refer to hydroacoustic "echo sounders" defined as active sound in water (sonar) used to study fish. Hydroacoustic assessments have traditionally employed mobile surveys from boats to evaluate fish biomass and spatial distributions. Conversely, fixed-location techniques use stationary transducers to monitor passing fish.
The word sounding is used for all types of depth measurements, including those that don't use sound, and is unrelated in origin to the word sound in the sense of noise or tones. Echo sounding is a more rapid method of measuring depth than the previous technique of lowering a sounding line until it touched bottom.
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The required precision and accuracy of the hydrographic echo sounder is defined by the requirements of the International Hydrographic Organization (IHO) for surveys that are to be undertaken to IHO standards.[2] These values are contained within IHO publication S44.
In order to meet these standards, the surveyor must consider not only the vertical and horizontal accuracy of the echo sounder and transducer, but the survey system as a whole. A motion sensor may be used, specifically the heave component (in single beam echosounding) to reduce soundings for the motion of the vessel experienced on the water's surface. Once all of the uncertainties of each sensor are established, the hydrographer will create an uncertainty budget to determine whether the survey system meets the requirements laid down by IHO.
https://en.wikipedia.org/wiki/Echo_sounding