Earphone body with tuned vents

Abstract

An earphone body includes an internal chamber, a transducer housed in the internal chamber, a first tuned vent and a second tuned vent. The transducer has a front surface facing a direction of insertion of the earphone body in use and a rear surface 6B. The internal chamber provides a proximal acoustic volume adjacent the front surface of the transducer and a distal acoustic volume adjacent the rear surface of the transducer. The first tuned vent and the second tuned vent each extend between the distal acoustic volume and the ambient environment and are adapted to provide fluid communication between the distal acoustic volume and the ambient environment. The first tuned vent is tuned to a first frequency and the second tuned vent is tuned to a second frequency, the first frequency being lower than the second frequency.

Claims

1. An earphone body comprising: an internal chamber; a transducer housed in the internal chamber, the transducer including a front surface facing in a direction of insertion of the earphone body in use and a rear surface; a first tuned vent; and a second tuned vent, wherein the internal chamber provides a proximal acoustic volume adjacent the front surface of the transducer, wherein the internal chamber provides a distal acoustic volume adjacent the rear surface of the transducer, wherein a primary acoustic opening is located in a front section of the internal chamber of the earphone body for allowing sound to exit the proximal acoustic volume to a user's ear, wherein the first tuned vent and the second tuned vent each extend between the distal acoustic volume of the internal chamber and an ambient environment and are adapted to provide fluid communication between the distal acoustic volume and the ambient environment, the first tuned vent and the second tuned vent are located in a rear section of the internal chamber of the earphone body, and both the first tuned vent and the second tuned vent are located on the same side of the transducer, and wherein the first tuned vent is tuned to a first frequency or range of frequencies and the second tuned vent is tuned to a second frequency or range of frequencies, the first frequency or range of frequencies being lower than the second frequency or range of frequencies.

2. An earphone body as claimed in claim 1, wherein the first tuned vent has a lower cross-sectional area to length ratio than the second tuned vent.

3. An earphone body as claimed in claim 1, wherein the first tuned vent has at least one dimension which is different to a dimension of the second tuned vent, where the dimension is selected from the group consisting of width, diameter, length and cross-sectional area in a direction perpendicular to the length.

4. An earphone body as claimed in claim 3, wherein the first tuned vent and/or the second tuned vent is circular in cross-section in a direction perpendicular to the length of the tuned vent.

5. An earphone body as claimed in claim 1, wherein the first tuned vent and/or the second tuned vent has a tubular shape.

6. An earphone body as claimed in claim 5, wherein the first tuned vent and/or the second tuned vent has a tubular shape with at least one bent section along the length of the vent.

7. An earphone body as claimed in claim 1, wherein the first tuned vent and/or the second tuned vent is positioned to opposed the rear surface of the transducer.

8. An earphone body as claimed in claim 1, wherein the first tuned vent and/or the second tuned vent is provided with at least one acoustic resistance means.

9. An earphone body as claimed in claim 8, wherein the acoustic resistance means comprises a woven mesh.

10. An earphone comprising the earphone body of claim 1.

11. A method of adjusting sound pressure levels output from an earphone to a user's ear using the earphone body of claim 1, the method comprising: sending an electrical signal to the transducer to produce sound waves in the proximal and distal acoustic volumes in the internal chamber of the earphone body; outputting the sound waves to be received by a user's ear; and transmitting sound waves from the distal acoustic volume to the ambient environment through the first tuned vent and the second tuned vent.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic diagram of an earphone body according to an embodiment of the present invention;

(2) FIG. 2 is a perspective view of the top of a portion of an earphone body with a section cut away to show cross-sections of a first tuned vent and a second tuned vent in the direction of their length;

(3) FIG. 3 is a graph of sound pressure level (SPL) (y axis) against frequency (Hertz) (x axis) for a tuned vent for low frequencies; and

(4) FIG. 4 is a graph of sound pressure level (SPL) (y axis) against frequency (Hertz) (x axis) for a tuned vent for mid-range frequencies.

DETAILED DESCRIPTION

(5) With reference to FIG. 1, an earphone body 2 comprises an internal chamber 4, a transducer 6, which is housed in the internal chamber 4, a first tuned vent 8 and a second tuned vent 10. The earphone body may be used for leaky type or sealed type earphones. The earphones may be intra-canal or intra-concha, as appropriate.

(6) The transducer 6 has a front surface 6A and a rear surface 6B. The front surface faces in the direction of insertion of the earphone body 2 into the entrance of a user's ear, in use of the earphone. The transducer 6 may be any type suitable for use within an earphone and is typically a driver (e.g., a speaker for receiving electrical signals). The transducer 6 is coupled to and operated by one or more electronic devices (not shown).

(7) The internal chamber 4 provides a proximal acoustic volume 12 adjacent the front surface 6A of the transducer 6. The internal chamber 4 also provides a distal acoustic volume 14 adjacent the rear surface 6B of the transducer 6.

(8) The first tuned vent 8 and the second tuned vent 10 each extend between the distal acoustic volume 14 of the internal chamber 4 and the ambient environment and are adapted to provide fluid communication between the distal acoustic volume 14 and the ambient environment.

(9) In this embodiment, the first tuned vent 8 and the second tuned vent 10 are located in a rear section 16 (e.g., a rear wall) of the earphone body 3, substantially opposing the rear surface 6B of the transducer 6 in this example. A front section 18 (e.g., a front wall) of the earphone body 2 is provided with a primary acoustic opening 20 for allowing sound to exit the proximal acoustic volume 12 for direction into a user's ear canal. This primary acoustic opening 20 substantially opposes the front surface 6A of the transducer 6 in this example.

(10) The earphone body 2 may be either the external casing of an earphone or a separate component within an earphone. The earphone body is adapted to receive digital or analog sound data for outputting sound to a user. The earphone body 2 may be formed of a rigid material (e.g., plastic). The internal cavity 4 houses internal components such as the transducer 6 and the earphone body 2 is designed to protect the internal components from damage.

(11) Referring to FIGS. 1 and 2, the first tuned vent 8 and the second tuned vent 10 are circular in cross-section in a direction perpendicular to the length of each vent. Alternatively, the first tuned vent 8 and the second tuned vent 10 may have a non-circular cross-sectional shape in a direction perpendicular to their lengths. For example, the tuned vents may have an oval or polygonal shape (e.g., rectangular, pentagonal, hexagonal) in cross-section. Also, the cross-sectional shape of the first tuned vent 8 in a direction perpendicular to its length may be different to the cross-sectional shape of the second tuned 10 vent in a direction perpendicular to its length.

(12) Each vent of this embodiment is tuned by selecting an appropriate length and diameter (and therefore cross-sectional area) for the vent. Referring to FIG. 2, first tuned vent 8 consists of two straight sections along its length that meet at an angle of between 100 to 150 degrees. The second tuned vent 10 also consists of two straight sections along its length that meet at an angle of approximately 90 degrees. However, one or both tuned vents may instead consist of a single straight section or may consist of three or more straight sections. Alternatively, one or both tuned vents may consist of one or more curved and/or straight sections. The sections of each vent are in fluid communication with each other.

(13) The length and diameter of the first tuned vent 8 are different to the length and diameter of the second tuned vent 10 in the present embodiment.

(14) Each vent is tuned for a specific frequency response by selecting, in particular, an appropriate cross-sectional area and length for the vent. The dimensions of the first tuned vent and the second tuned vent are calibrated to provide distinct frequency responses, with the first tuned vent 8 being tuned to a lower frequency or range of frequencies than the second tuned vent 10.

(15) The ratio of cross-sectional area to length defines the tuning frequency, given a fixed distal volume. A smaller ratio will result in a vent tuned to lower frequencies.

(16) Referring to FIGS. 1 and 2, the second tuned vent 10 has a greater cross-sectional area and a shorter length than the first tuned vent 9. The first tuned vent 8, therefore, has a lower ratio of diameter to length than the second tuned vent, together with a lower ratio of cross-sectional area to length than the second tuned vent 10.

(17) The first tuned vent 8 may be tuned to a low frequency or to a low frequency range, for example frequencies between 50 Hz and 800 Hz. The second tuned vent 10 may be tuned to a middle frequency or to a mid-frequency range, for example frequencies between 800 Hz and 4 kHz. The first tuned vent 8 and the second tuned vent 10 may be tuned to distinct or to overlapping frequency ranges.

(18) By way of example only, a representative length for the first tuned vent 8 is 5 mm and a representative diameter for the first tuned vent 8 is 1 mm. The diameter to length ratio for the first tuned vent 8 in this example is, therefore, 1:5 and the cross-sectional area to length ratio for the first tuned vent 8 in this example is 79:500. Assuming a distal acoustic volume of approximately 1 cm.sup.3, this results in a tuning frequency of approximately 650 Hz.

(19) By way of example only, a representative length for the second tuned vent 10 is 2 mm and a representative diameter for the second tuned vent 10 is 1.5 mm. The diameter to length ratio for the second tuned vent 10 in this example is, therefore, 3:4 and the cross-sectional area to length ratio for the second tuned vent 10 in this example is 177:200. Assuming a distal acoustic volume of approximately 1 cm.sup.3, this results in a tuning frequency of approximately 1300 Hz.

(20) The sound pressure level in the earphone body 2 may be enhanced or reduced by providing an amount of acoustic resistance for the first tuned vent 8 and/or the second tuned vent 10. In one embodiment, one or more forms of acoustic resistance are provided in series with the acoustic mass of the first tuned vent 8 and/or the second tuned vent 10. Acoustic resistance relates to the loss of energy of a sound wave and so providing an acoustic resistance means in series with the acoustic mass reduces the energy of a sound wave.

(21) The acoustic resistance means may be in the form of a woven acoustic mesh. The acoustic resistance means may be placed over at least one opening of one or both of the tuned vents. Alternatively, or in addition the acoustic resistance means may be placed inside one or both of the tuned vents. By way of example, the woven mesh may be affixed by adhesive or friction or snap-fitted into place. It will be appreciated that other forms of acoustic resistance means may be used in addition or as an alternative. An acoustic resistance means has an associated resistance value which may be expressed in Rayleighs where 1 Rayleigh (1 Rayl) equals 1 pascal-second per meter.

(22) By balancing factors such as acoustic resistance the frequency response for mid-range frequencies and low frequencies (e.g., bass frequencies) can be optimized optimised for the corresponding tuned vent.

(23) FIGS. 3 and 4 are graphs of sound pressure level (SPL) against frequency (Hertz), with the graph of FIG. 3 relating to the effect of varying degrees of acoustic resistance on a first tuned vent 8, which is tuned to lower (low) frequencies, and FIG. 4 relating to the effect of varying degrees of acoustic resistance on a second tuned vent 10, which is tuned to higher (mid-range) frequencies.

(24) The graphs of these figures have been prepared using a computer simulation. The dual vent system has also been measured on real samples, but the simulation allows for varying the acoustic resistance parameter with greater detail for better visual representation.

(25) As shown in FIG. 3, an increase in the amount of acoustic resistance results in a decrease in sound pressure in the lower frequencies.

(26) Conversely, with reference to FIG. 4, as the acoustic resistance is increased, there are greater sound pressure levels at higher frequencies, such that lower acoustic resistance may be preferable for the second tuned vent 10 to allow for amplification of the mid-range frequencies.

(27) The earphone and the earphone body 2 of the present invention may include other components including but not limited to a battery, transceiver, Micro USB charge port, capacitor, Bluetooth® module, magnet and microphone. The internal components of the earphone and of the earphone body 2 may be arranged in any configuration which provides acceptable, preferably optimal, acoustic performance.

(28) The tuned vents of the present invention are not holes or openings for microphones or sensors.

(29) The invention has been described above with reference to a specific embodiment, given by way of example only. It will be appreciated that different configurations are possible, which fall within the scope of the appended claims.