Acoustic frequency responses in a conventional classroom

# Classroom frequency responses Repository with room frequency responses, measured at the Technical University of Denmark, DK-2800 Kgs. Lyngby, DTU building 352, lecture room 019, during August 9th-13th 2019. The measurements were conducted by Samuel A. Verburg and Manuel Hahmann (ORCID https://orcid.org/0000-0001-7325-3584). This work is funded by Villum Fonden through Villum Young Investigator grant number 19179 for the project 'Large-scale Acoustic Holography'. This dataset is licensed under CC BY 4.0. Please cite as Hahmann, Manuel; Verburg Riezu, Samuel Arturo (2021): Acoustic frequency responses in a conventional classroom. Technical University of Denmark. Dataset. https://doi.org/10.11583/DTU.13315286 Feel free to get in touch if you have questions or would like to access the data in higher resolution. ## Room The classroom has dimensions (l_x, l_y, l_z) = (6.63, 9.45, 2.97) m and volume of V = 186 m^2, a reverberation time of approx.~T_{60} = 0.5 s and a Schröder frequency of f_S = 240Hz. The classroom has a wooden floor and an absorbing ceiling. One side along the long dimension has a large window front with radiators. The other walls have black- and whiteboards and a few absorbing elements. The room is furnished with standard classroom furniture (see picture). ## Setup A UR5 robotic arm (Universal Robots, Odense, Denmark) was used to precisely and automatically position a 1/2 inch free field condenser measurement microphone (Brüel&Kjäer, Nærum, Denmark) at the measurement positions. A BM6 loudspeaker (Dynaudio, Skanderborg, Denmark) placed in a room corner was used to excite the room with 10s wideband logarithmic sweeps. ## Measurement The measured impulse responses reach from 20 Hz to 20 kHz with 0.1 Hz resolution. (1 Hz resolution included in the data set) The responses were measured over planar, square apertures of size 1.7 x 1.7 m^2 and regular position grids. - At z = 1816 mm, a total of 1225 impulse responses were measured distributed over a planar regular grid with 50 mm spacing. - At z = 1866 mm, a total of 4761 impulse responses were measured distributed over a planar regular grid with 25 mm spacing. - At z = 1916 mm, a total of 1225 impulse responses were measured distributed over a planar regular grid with 50 mm spacing. ## Repository content - classroom_readme.md : this readme - classroom_sketch.pdf : sketch drawing - classroom_photo.pdf : photograph - classroom_frequency_responses.h5 : Hierarchical Dataset with RIRs - 'aperture_z1866mm': measurements at z = 1866 mm - frequency : frequency vector in 1 Hz steps between 0 and 5 kHz (5001) - id : measurement sequence ordering (4761) - xyz : measurement position (x,y,z) in mm (4761x3) - timestamp : timestamp for each measurement [year, month, day, hours, minutes, seconds] (4761x6) - response : response for each frequency and position (5001x4761)  

# 丹麦技术大学教室频响数据集仓库
测量地点位于丹麦灵比（DK-2800 Kgs. Lyngby）的丹麦技术大学352号楼019报告厅，测量时间为2019年8月9日至13日。本次测量由Samuel A. Verburg与Manuel Hahmann完成（ORCID：https://orcid.org/0000-0001-7325-3584）。

本研究由维鲁姆基金会（Villum Fonden）通过维鲁姆青年研究者项目（资助编号19179）资助，项目名称为"大规模声学全息术（Large-scale Acoustic Holography）"。本数据集采用CC BY 4.0许可协议发布，引用格式如下：Hahmann, Manuel; Verburg Riezu, Samuel Arturo (2021): 常规教室中的声学频响。丹麦技术大学。数据集。https://doi.org/10.11583/DTU.13315286。如有疑问或需要获取高分辨率数据，请随时联系。

## 教室概况
该教室尺寸为(l_x, l_y, l_z)=(6.63, 9.45, 2.97)米，体积V=186 m³，混响时间约为T_{60}=0.5秒，施罗德频率f_S=240 Hz。教室地面为木质地板，天花板为吸声结构。沿长边的一侧设有带散热器的大面积玻璃窗幕墙，其余墙面配备黑白板及少量吸声构件。教室内布置标准教室家具（详见照片）。

## 测量装置
本次测量采用UR5机械臂（UR5 robotic arm，优傲机器人公司（Universal Robots），丹麦欧登塞），用于精准自动定位1/2英寸自由场传声器（Brüel&Kjäer，丹麦奈鲁姆）至各测量点位。在房间角落放置BM6扬声器（丹拿音响（Dynaudio），丹麦斯坎讷堡），以10秒宽带对数扫频信号激励房间声学环境。

## 测量参数
本次测量的脉冲响应覆盖20 Hz至20 kHz频段，频率分辨率为0.1 Hz（数据集中包含1 Hz分辨率版本）。测量点位分布于1.7×1.7 m²的平面正方形孔径内，采用规则网格布局：
- 在z=1816 mm高度处，采用50 mm间距的平面规则网格，共采集1225条脉冲响应
- 在z=1866 mm高度处，采用25 mm间距的平面规则网格，共采集4761条脉冲响应
- 在z=1916 mm高度处，采用50 mm间距的平面规则网格，共采集1225条脉冲响应

## 数据集仓库内容
- classroom_readme.md：本说明文档
- classroom_sketch.pdf：教室布局示意图
- classroom_photo.pdf：教室实景照片
- classroom_frequency_responses.h5：包含房间脉冲响应的分层数据集
- aperture_z1866mm：z=1866 mm高度处的测量数据
- frequency：0至5 kHz的1 Hz步长频率向量（共5001个点）
- id：测量序列编号（共4761条）
- xyz：测量点位坐标(x,y,z)，单位为毫米（维度为4761×3）
- timestamp：每条测量的时间戳，格式为[年, 月, 日, 时, 分, 秒]（维度为4761×6）
- response：各频率对应各点位的频响数据（维度为5001×4761）