A sound-absorbing panel comprising a first layer of sound-absorbing material, a second layer of sound-absorbing material, and an integrated frame supporting the first layer of sound-absorbing material and the second layer of sound-absorbing material; the first layer of sound-absorbing material having a first front surface apt to be directly exposed to an acoustic source for being struck by sound waves without the interposition of grated elements or other parts, a first rear surface opposite the first front surface, and a first lateral surface delimited between the first front surface and the first rear surface; the second layer of sound-absorbing material having a second front surface facing towards said first rear surface and separated from the external environment by means of the first layer of sound-absorbing material, a second rear surface opposite the second front surface, and a second lateral surface delimited between the second front surface and the second rear surface; wherein the frame includes: - a support profile laterally surrounding at least part of the first layer of sound-absorbing material and of the second layer of sound-absorbing material and having an abutment wall for said first lateral surface and second lateral surface and a flange projecting from the abutment wall; - a protective sheet resting against the flange of the support profile and defining, in turn, an abutment element for said second rear surface, so that the second layer of sound-absorbing material is interposed between the first layer of sound-absorbing material and the protective sheet itself; and - at least one containment bracket having a fixing portion fixed to the support profile and a containment portion cooperating with the first layer of sound-absorbing material at said first front surface; wherein the sound-absorbing material of the first layer is made of natural or artificial resin-bonded fibres; wherein the first layer of sound-absorbing material and the second layer of sound-absorbing material are releasably interposed and fitted between said containment portion and the protective sheet; and wherein the panel further comprises a layer of anti-vibration material interposed between the frame and said first layer of sound-absorbing material and second layer of sound-absorbing material. the first layer of sound-absorbing material having a first front surface apt to be directly exposed to an acoustic source for being struck by sound waves without the interposition of grated elements or other parts, a first rear surface opposite the first front surface, and a first lateral surface delimited between the first front surface and the first rear surface; the second layer of sound-absorbing material having a second front surface facing towards said first rear surface and separated from the external environment by means of the first layer of sound-absorbing material, a second rear surface opposite the second front surface, and a second lateral surface delimited between the second front surface and the second rear surface; wherein the frame includes: - a support profile laterally surrounding at least part of the first layer of sound-absorbing material and of the second layer of sound-absorbing material and having an abutment wall for said first lateral surface and second lateral surface and a flange projecting from the abutment wall; - a protective sheet resting against the flange of the support profile and defining, in turn, an abutment element for said second rear surface, so that the second layer of sound-absorbing material is interposed between the first layer of sound-absorbing material and the protective sheet itself; and - at least one containment bracket having a fixing portion fixed to the support profile and a containment portion cooperating with the first layer of sound-absorbing material at said first front surface; - a support profile laterally surrounding at least part of the first layer of sound-absorbing material and of the second layer of sound-absorbing material and having an abutment wall for said first lateral surface and second lateral surface and a flange projecting from the abutment wall; - a protective sheet resting against the flange of the support profile and defining, in turn, an abutment element for said second rear surface, so that the second layer of sound-absorbing material is interposed between the first layer of sound-absorbing material and the protective sheet itself; and - at least one containment bracket having a fixing portion fixed to the support profile and a containment portion cooperating with the first layer of sound-absorbing material at said first front surface; wherein the sound-absorbing material of the first layer is made of natural or artificial resin-bonded fibres; wherein the first layer of sound-absorbing material and the second layer of sound-absorbing material are releasably interposed and fitted between said containment portion and the protective sheet; and wherein the panel further comprises a layer of anti-vibration material interposed between the frame and said first layer of sound-absorbing material and second layer of sound-absorbing material.