Da kanskje vi skulle avlive den ekspertmyten som uforbeholdent sier at subber under en viss frekvens ikke er direktive. På en eller annen måte kan de lokaliseres.
Bra du konkluderer som du gjør.
Kan man lokalisere lave frekvenser? "Fasit" er vel som vanlig at det kommer an på.
Ja, det er utrolig hva man finner ut om man prøver litt sjæl.;D
I en fagartikkel fra 2012, med tittelen "Towards a generalized theory of low-frequency sound source localization", konkluderer forfatterne med at lokalisering av lave frekvenser er mulig gitt konkrete karakteristika i avspillingsscenariet. Denne konklusjoen står i kontrast til en del tidligere forskning. Forfatterne påpeker imidlertid at lokalisering ikke alltid vil lykkes; det kommer an på. Blant annet betyr rommets størrelse en del for evnen til å lokalisere. Også lytteavstand fra bassen spiller inn. Forfatterne foreslår en modell som forutsier vår evne til å lokalisere subwoofere.
For øvrig har fagartikkelen også en litteraturgjennomgang. Her konkluderer de med at tidligere studier fordeler seg omtrent 50-50 mellom dem som finner at subwoofer kan lokaliseres og dem som mener at lave frekvenser ikke kan lokaliseres.
(Og det hele er litt mer komplekst enn ved første øyekast, for hvis man bruker subwoofer i et oppsett som distribuerer egenstøy eller forvrengning, vil subben være lettere identifiserbar).
Sånn sett oppmuntrer fagartikkelen til å bruke egne ører; "tenke sjæl", som Trond Viggo sa. Og gamle kjerringråd som å sørge for symmetri og en tydelig venstre-høyre-fordeling av subber som står i nærheten av hovedhøyttalerne blir i alle fall ikke avlivet.
Her er lenken til fagartikkelen:
https://www.researchgate.net/public...ry_of_low-frequency_sound_source_localization
Og for enkelhets skyld klipper jeg inne hele konklusjonen:
"4 CONCLUSIONS & FUTURE WORK
This research provides a first step towards a generalized understanding of low-frequency sound
source localization. It by no means provides a definitive answer to this long-standing question, but
presents some objectively-obtained data to confirm or disprove many of the conflicting hypotheses
regarding this subject.
First, the work confirmed what most researchers have previously suggested: below around 200 Hz,
low-frequency localization in small rooms tends becomes impaired. This frequency limit, however, is
not one-size-fits-all (as Greisinger suggested13), but depends largely on room dimensions. Larger
rooms allow for localization of lower frequencies, but smaller rooms prevent any noticeable
directionality in the subwoofer band.
Furthermore, both simulation and subjective results in this work highlight the importance of listener
location. Listeners closer to a subwoofer benefited from a longer duration of uncorrupted ITD cues
while listeners located further away exhibited directional confusion. This is a point that has not been
addressed in the literature, although it appears to be a crucial aspect in understanding this subject.
The bulk of the reviewed work only examines centrally-located listening points, which
characteristically gives poor localization due to phase issues8,14.
While the equations stemming from the simulation results (Eqs. 3.1 & 3.2) give calculations for the
number of uncorrupted wavelengths for localization (factoring in frequency, room dimensions and
listener location), they do not indicate the minimum number of wavelengths necessary for accurate
localization (or room absorptive properties, which must be examined at some point).
Analyzing the findings of previous work, however, a picture emerges of this wavelength
requirement. Borenius’ work3 indicated that minimal localization is possible below 200 Hz in a 7.0 m
x 5.2 m room. Using the derived equations in this work, the configuration should give 2.4
uncorrupted wavelengths at 200 Hz (with 1.2 wavelengths at 100 Hz, where it is indicated that no
directional information is noticeable). Similarly, Kelloniemi et al.5 showed that directional information
is not necessary below 120 Hz in a 6.25 m x 5.58 m room. This corresponds to 1.5 uncorrupted
wavelengths. Zacharov et al.6 proposed that localization is effective down to 85 Hz in a 5.03 m x
6.03 m room, which gives one uncorrupted wavelength. Lastly, Kugler and Theile7 state that one
subwoofer is ample for frequencies below 100 Hz in a 6.68 m x 6.62 m room, corresponding to 1.4
uncorrupted wavelengths.
Three of the four works support the minimum number of uncorrupted wavelengths for accurate
localization is around 1.4. This may be a good initial suggestion for determining what frequencies
can be localized in a room. If a listener receives more than 1.4 uncorrupted wavelengths, the source
is localizable at and above that frequency. It must be noted, though, that the wavelength calculation
for each of these results was based on the assumption that the listening location in the tests was in
the room center. The data in this research has indicated that localization is sensitive to listener
location; therefore the 1.4 wavelength suggestion must be investigated in future work.
Overall, it appears that certain low-frequency signals can be localizable under the right conditions.
Large venues (such as cinemas, theaters, clubs, auditoriums and outdoor sites) should not
contribute significantly to impairment of low-frequency directional data and may actually benefit from
the employment of multichannel subwoofers. It has yet to be determined, however, if directional
low-frequencies impacts the overall listening experience when high-frequency localization cues are
also present, although from an artistic perspective the reproduction of signals that are
predominantly low-frequency may well be enhanced by improved directionality. This is a key
question for future work as are methodologies for enhancing low-frequency directionality in smaller
listening spaces. Nevertheless, it seems the conjecture that humans cannot localize lowfrequencies
is inaccurate and, in reality, the question concerning localization demands the
response: “it depends”".
