Piezoelectric acoustic component

A piezoelectric acoustic component comprising:

• a piezoelectric sounding element including a diaphragm made of metal and a piezoelectric element provided on at least one surface of the diaphragm;
• and
• a case that fixes an outer peripheral portion of the diaphragm of the piezoelectric sounding element across an entire circumference, forms a first space and a second space on both sides of the piezoelectric sounding element, and configures a resonator in which one or more sound emission holes are formed in a wall portion facing the first space,
• wherein a non-fixed portion located inside the outer peripheral portion of the diaphragm includes a pair of long sides that face each other, a pair of short sides, shorter than the long sides, that face each other, and a pair of recesses, provided in the pair of long sides, that protrude so as to approach each other,
• the piezoelectric element is provided in a region between the pair of recesses of the non-fixed portion of the diaphragm,
• both a contour shape of the diaphragm and a contour shape of the piezoelectric element are defined so as to be symmetric with respect to a first imaginary line that bisects the pair of short sides and symmetric with respect to a second imaginary line that bisects the pair of long sides,
• ratio L1/W1 of length L1 of the long sides to length W1 of the short sides is defined so as to fall within a range from 1.25 to 1.75,
• ratio L2/L1 of length L2 of an opening opened in the long sides of the recesses of the non-fixed portion of the diaphragm to length L1 of the long sides is 0.4 to 0.7 and ratio W2/W1 of dimension W2 between the pair of recesses in the direction toward the second imaginary line to the length W1 of the short sides is 0.4 to 0.95, and
• a total opening area of the one or more sound emission holes and an air chamber capacity of the resonator are defined such that sound pressures at a primary resonance frequency, a tertiary resonance frequency, and an intermediate frequency between the primary resonance frequency and the tertiary resonance frequency when a sine wave signal is input as an input signal are 80 dB or more.