DESCRIZIONE
This disclosure provides a detection apparatus (1, 1a, 1b, 1c) that includes a transducer (2, 2a) configured to transmit a transmission wave, a first echo intensity calculator (12, 12c) configured to calculate a first echo intensity of a first reception signal generated from a reception wave resulting from a reflection of said transmission wave on reflection objects, a second echo intensity calculator (13, 13c) configured to calculate a second echo intensity of a second reception signal generated from a reception wave resulting from a reflection of said transmission wave on said reflection objects, a signal duration of said second reception signal being shorter than that of said first reception signal, a frequency distribution generator (14,15) configured to generate a first frequency distribution of said first echo intensity and to generate a second frequency distribution of said second echo intensity, and a density extractor (18) configured to extract a density of said reflection objects or an index of density of said reflection objects based on a degree of similarity between said first frequency distribution and said second frequency distribution as a result of a comparison of said first frequency distribution and said second frequency distribution. [Image Omitted]