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Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →NASA’s full-scale acoustic campaign found that Joby’s electric aircraft made different levels of noise in different flight phases: full wing-borne flight was the quietest mode tested, while approaches were consistently louder than departures within the study’s 75 dBA ground contours. Joby later reported a 45.2 dBA equivalent overhead value for a specific 100-knot flyover case and levels below 65 dBA during planned takeoff and landing profiles. Those figures describe different test conditions—not a single noise rating for every flight or location.
What NASA measured
NASA and Joby conducted the acoustic field campaign over two weeks in September 2021 at Joby’s Electric Flight Base near Big Sur, California. NASA describes it as the first full-scale test of an advanced air mobility aircraft over conditions representative of a typical mission profile. The campaign covered hover, takeoff, cruise and landing, gathering more than 100 test points across 31 unique conditions.
NASA’s technical paper specifies a 58-channel distributed microphone array; NASA’s public explainer describes the setup as using more than 50 microphones. Researchers synchronized sound measurements with aircraft position and state data, then used the results to map ground noise contours for departures and approaches at different flight-path angles and accelerations. The work also included directivity maps from constant-airspeed flyovers and hover measurements in and out of ground effect. NASA’s technical paper gives the study methods and comparative findings.
What the headline noise figures mean
| Reported figure | Condition and method | How to interpret it |
|---|---|---|
| 45.2 dBA at 1,640 feet (500 meters) | Joby’s May 2022 account of six overhead flyovers at 100 knots. NASA processed the field recordings into an acoustic hemisphere; Joby applied standard spherical spreading and atmospheric attenuation to report an average free-field overhead value. | A processed, Joby-published equivalent for this flyover case, not a direct reading that applies to every distance or operation. |
| Below 65 dBA at 330 feet (100 meters) | Joby’s May 2022 account of NASA engineers measuring planned takeoff and landing profiles. Joby says the campaign included more than 20 takeoff and landing tests over the microphone array. | A figure tied to those planned profiles and that distance; it is not interchangeable with the overhead-flyover result. |
Both figures come from Joby’s May 2022 account of the NASA campaign. They are not like-for-like measurements: one is an overhead case at 100 knots and 500 meters, while the other concerns takeoff and landing profiles at 100 meters. Neither establishes the sound level at every point around the aircraft or for every operating condition.
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- 2.25-inch LCD Screen with Backlight: This TS-501B sound level meter is measured noise levels are expressed in decibels and displayed on the 2.25-inch LCD screen, it easy to read on a big display design. Long press the backlight button to turn on a backlight, making it easy to view even in dim light
- Decibel Meter with A/C Weighting: TopTes TS-501B decibel meter uses a precise condenser microphone to capture sound. It’s equipped with A-weighting and C-weighting facilities that measure noise levels from 30 to 130 dB with an accuracy of 1.5 dB, Frequency from 30 to 8000Hz. Perfect for monitoring noise levels in communities, home theaters, audio systems, automobiles, workshops, schools, offices, factories
- MAX/MIN Measurement: The sound pressure level (SPL) meter has Max or Min measurement values to represent the maximum/minimum (high/low peak) value of the sound produced within a certain time, and the data hold function can freeze the current reading based on the sound measurement according to individual needs
- Easy Use and Feature Packed: The non-slip side design ensures that the portable noise meter fits easily in the hand. TS-501B SPL meter is a battery-operated noise meter that comes with three durable batteries and has an automatic power off function to extend battery life. A low battery indicator will appear on the screen when the battery is low to remind the user to replace the battery in time
- What’s in the Box: One TS-501B Decibel Meter, Three AAA Batteries, One User Manual, One Carry Case. The device has been factory calibrated to ensure high measurement accuracy and compliance with quality standards.
Why Joby’s eVTOL has no single noise signature
Flight phase changes the result
NASA found full wing-borne flight to be the quietest mode in the tested envelope. In comparisons of ground areas within the 75 dBA contours, approaches consistently showed higher noise levels than departures. A number from cruise or an overhead flyover therefore cannot stand in for hover, approach or departure.
Hover readings varied between runs
NASA reported 2 to 5 dB of variation during a single hover run, with more significant variation between back-to-back runs. That variability is one reason to avoid treating a single measurement as a fixed aircraft rating.
Rank #2
- Accurate 30-130dB Noise Measurement: The Goldeep SL750A decibel meter measures sound levels from 30 to 130dB with ±1.5dB accuracy and a 31.5Hz-8KHz frequency response. This sound decibel meter is ideal for checking home noise, neighbor noise, traffic sound, office noise, construction sites, factories, classrooms, baby rooms and musical instruments.
- A/C Weighting for Different Sound Environments: This digital sound level meter supports A/C weighting modes for more flexible noise testing. A-weighting is suitable for environmental noise such as urban traffic, schools, offices, business areas and construction sites. C-weighting is designed for industrial noise from machinery, equipment, aerospace, high-speed rail and other high-intensity sound sources.
- dB/SONE Units for Sound & Loudness Testing: Use the dB unit to measure sound intensity for environmental noise, machine noise, traffic noise and workplace noise. Switch to SONE to better understand perceived loudness, making this db meter useful for music, audio systems, acoustic checks and instrument noise control..
- FAST/SLOW Response with MAX/MIN Tracking: The spl meter includes FAST and SLOW response settings. FAST response, 0.125s per reading, is useful for changing noise levels, while SLOW response, 1s per reading, is suitable for steady-state noise. MAX/MIN value tracking helps record peak and minimum noise levels over a period of time.
- Easy-to-Use Sound Meter for Daily & Professional Needs: Designed with data hold, clear LCD display, anti-slip grip and a windbreak ball, this sound meter is practical for indoor and outdoor use. Package includes 1 sound level meter, 2 AAA 1.5V batteries and 1 user manual, so you can start measuring noise right away.
Operating and atmospheric conditions matter
NASA identifies aircraft speed and weight, rotor count and speed, and atmospheric conditions such as weather as factors that affect sound measurements. A careful comparison needs to align the flight phase, aircraft state, distance and microphone geometry, sound metric and weighting, averaging or equivalent-level processing, and ambient conditions.
What later NASA studies add
A 2024 NASA paper used Vold-Kalman order tracking on synchronized flight-test data to separate harmonic and nonharmonic sound and distinguish individual propeller contributions. Its examples include a 60-knot flyover and hover. This analysis helps researchers examine the components of the aircraft’s overall sound field; it does not turn the 2022 headline values into universal operating figures. NASA’s 2024 propeller source-separation paper describes the method.
Rank #3
- ✅【Decibel Meter Data Logger】DANOPLUS decibel meter is able to record up to 43,000 data, it could view on the main unit & PC, and also export data via excel file whlie connecting to PC
- ✅【Three-Color Light Alarm】The decibel meter sound level reader is equipped with 3-color light, alerts you with green, yellow, and red indicators for low, medium, and high noise levels, you may manually set the alarm threshold
- ✅【High Accuracy】 The noise decibel meter is measuring range from 30~130dB and +/-1.5dB accuracy, colored screen with line chart display with visual noise data changes, analog bars, date and time ( (year-month-day-hour-minute-second)
- ✅【A/C Frequency Weighting】The db meter can switch between bB A and C frequency with adjustable FAST / SLOW measuring response; and comes with DC output the noise value by voltage mode according to the proportion
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In a 2025 wind-tunnel study of an S4 propeller, NASA examined blade pitch, RPM, flow angle and wind speed. The paper reports an optimum RPM for a specific thrust level from a noise perspective, and notes that reducing RPM further can increase noise. Rotor speed alone is therefore not enough to predict whether a particular operating point will be quieter. NASA’s 2025 propeller test paper describes those results.
Does the test prove Joby’s aircraft is quiet?
The campaign provides measured and processed evidence about sound under specified test conditions, plus comparisons between phases. It does not certify the aircraft as “quiet,” establish a universal noise level, or determine how every person will experience it. NASA distinguishes objective noise measurements from the subjective element of listener perception. Its May 2026 review identifies human response, measurement metrics, ground and flight testing, tool validation and policy as continuing areas of work. NASA’s 2025 urban air mobility noise review discusses those open areas.
Rank #4
NASA’s May 2022 explainer describes the campaign’s purpose as gathering performance and acoustic data to support future modeling. Shivanjli Sharma, then acting lead for NASA’s AAM National Campaign, said: “We will use this data to help us understand the vehicle’s performance characteristics, the acoustics profiles, as well as information that will help us develop modeling scenarios.” NASA’s campaign explainer also outlines why aircraft and weather conditions affect measurements.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Can you compare it directly with a helicopter?
Not from these results alone. The cited NASA and Joby materials do not provide an apples-to-apples helicopter test. A meaningful comparison would need to match flight phase, distance and measurement geometry, speed and aircraft operating state, dBA metric and weighting, averaging method, and ambient or weather conditions. Without those matched conditions, a helicopter figure from another test cannot establish which aircraft would sound quieter in a particular setting.
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Quick Recap
Best Value
- 【Widely Used】The noise meter is the use of environmental sound level instrument, can be widely used in such as factories, workshops, schools, residential, office areas, traffic roads, audio and other occasions of sound level measurement. Also suitable for noise engineering, product quality control, health,prevention and control.
- 【Accurate Measurement】Measuring Range:30~130dB ;Accuracy:±1.5dB（94dB@1KHz）;Display Resolution:0.1dB
- 【A Weighted Measurement】 A Weighted network (automatic switching range display)
- 【Fast/Slow mode selection】Press the MODE key, you can convert the response speed of the noise meter, FAST fast, SLOW slow
- 【MAX/MIN Measurement】Press RANGE key to measure the maximum value of MAX and minimum value of MIN.A maximum duration of more than 3 seconds is recorded, with a normal test sampling rate of 0.5 seconds. The maximum error is ± 5%.
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