Abstract: Provided is a method of estimating a speed of a vehicle includes obtaining time domain acoustic data from an acoustic storage apparatus when the vehicle passes over a horizontally grooved road; calculating frequency domain acoustic data from the time domain acoustic data by using Fourier transformation; calculating, from the frequency domain acoustic data, a resonance frequency of sound generated between tires of the vehicle and horizontal groovings in the road; and estimating the speed when the vehicle passes over the horizontally grooved road by multiplying the resonance frequency by an interval of the horizontal groovings.

Abstract: Provided is a method of estimating a speed of a vehicle includes obtaining time domain acoustic data from an acoustic storage apparatus when the vehicle passes over a horizontally grooved road; calculating frequency domain acoustic data from the time domain acoustic data by using Fourier transformation; calculating, from the frequency domain acoustic data, a resonance frequency of sound generated between tires of the vehicle and horizontal groovings in the road; and estimating the speed when the vehicle passes over the horizontally grooved road by multiplying the resonance frequency by an interval of the horizontal groovings.

Abstract: Provided is a method of determining a recording time of an event data recorder (EDR) includes obtaining, from the EDR of a vehicle, main engine revolutions per minute (RPM) record data of which the recording time is unknown; obtaining, from an acoustic storage apparatus, time domain acoustic data including acoustic information of an event time of the vehicle; calculating frequency domain acoustic data from the time domain acoustic data by using Fourier transformation; calculating RPM estimation data of the vehicle of the event time from the frequency domain acoustic data by using order analysis; and determining whether a time when the EDR records the RPM record data is identical to the event time by comparing the RPM estimation data of the vehicle with the RPM record data.

Abstract: Provided is a method of estimating velocity of a vehicle, in which at least one black box is installed, the method including: receiving acoustic information from the black box, the acoustic information being synchronized with time of a certain image; transforming the acoustic information of a time domain to frequency data of a frequency domain via fast Fourier transformation (FFT); calculating revolutions per minute (RPM) of a main engine from the frequency data by using order analysis; and calculating velocity of the vehicle at the time of the certain image by using the RPM of the main engine and vehicle information.