Tatjana Miljković

Unmanned aerial vehicles open new possibilities for developing technologies that support more sustainable and efficient agriculture. This paper presents a non-invasive method for repelling rodents from crop fields using ultrasound. The proposed system is implemented as a spherical-cap ultrasound loudspeaker array consisting of eight transducers, mounted on a drone that overflies the field while emitting sound in the 20–70 kHz range. The hardware design includes both the loudspeaker array and a custom printed circuit board hosting power amplifiers and a signal generator tailored to drive multiple ultrasonic transducers. In parallel, a genetic algorithm is used to compute flight paths that maximize coverage and increase the probability of driving rodents away from the protected area. As part of the validation phase, artificial intelligence models for rodent detection using a thermal camera are developed to provide quantitative feedback on system performance. The complete prototype is evaluated through a series of experiments conducted both in controlled laboratory conditions and in the field. Field trials highlight which parts of the concept are already effective and identify open challenges that need to be addressed in future work to move from a research prototype toward a deployable product.

Izraženo prisustvo fantomskih parcijala u spektrima tonova harfe otvara pitanje njihovog uticaja na percepciju zvuka. Iako su fizički mehanizmi njihovog nastanka već razmatrani, perceptivna istraživanja do sada su uglavnom bila ograničena na klavir i na ukupni doprinos longitudinalnih komponenti, a ne na izdvojeni uticaj fantomskih parcijala. U ovom radu predstavljen je subjektivni AB test za ispitivanje uticaja fantomskih parcijala na percepciju tonova harfe. Test signali sintetisani su na osnovu realnih tonova harfe primenom aditivne sinteze, pri čemu su fantomski parcijali uključeni na frekvencijskim pozicijama na kojima se očekuju u realnim signalima. Amplitude fantomskih parcijala određene su na osnovu amplituda odgovarajućih roditeljskih parcijala, a zatim dodatno skalirane radi ispitivanja efekta njihove izraženosti. Predloženi eksperimentalni okvir predstavlja osnovu za buduća istraživanja uticaja fantomskih parcijala na opažaj boje tona, kao i njihovog združenog dejstva sa inharmoničnošću na konsonantnost i disonantnost intervala žičanih muzičkih instrumenata.

The pronounced presence of phantom partials in the spectra of harp tones constitutes a considerable challenge to the accurate estimation of the inharmonicity coefficient. Given the importance of the inharmonicity coefficient in tone synthesis and analysis of stringed musical instruments, a precise and automated estimation method is essential across the entire instrument register. To address this, a modification of the partial frequency deviation (PFD) algorithm was proposed, aimed at identifying and excluding phantom partials during inharmonicity estimation. The modified PFD algorithm was evaluated using a set of synthesized signals with systematically varied parameters, as well as a collection of recorded concert harp tones. Experimental results demonstrated that for 64% of real tones, the modified PFD algorithm yielded more accurate inharmonicity coefficient estimates compared to the original PFD algorithm, with improvements reaching up to 88.5% for certain tones. The accuracy of the inharmonicity coefficient estimation was found to depend primarily on the ratio between the number of phantom partials and the total number of partials used for estimation, as well as the spectral position and grouping of these phantom partials.

Rodents pose a significant threat to agriculture by damaging crops, spreading disease, and contaminating soil. To counter this, farmers often resort to chemical pesticides, which can harm ecosystems, or to non-chemical deterrents that tend to be less effective and subject to rodent adaptation. As a sustainable alternative, the RODENT project, Rodent Obstruction through Drone-Enabled Non-invasive Technology, introduces a dronemounted ultrasound system designed to emit high-frequency signals that deter rodents without harming the environment. In the initial design phase of the project, the first experiments were conducted in anechoic conditions to evaluate the acoustic performance of low-cost ultrasound speakers driven by a custom signal generator and amplifier. Results showed that both attenuation with distance and speaker directivity were within the expected range for rodent-sensitive frequencies, particularly at 70 kHz. However, the presence of side and rear lobes highlighted the need for improved directionality. Obtained results show that the proposed method effectively generates ultrasound signals within the targeted rodent-sensitive frequency range and validates the idea of using low-cost speakers in drone-mounted deterrence systems.

Recent papers and studies over the course of last three years have shown that COVID-19 has a negative impact on the speech communication quality between people. This paper presents an influence analysis of the curvature shape of protective transparent shields on the speech signal. Five shields made of the same material and dimensions but with different curvatures were analyzed, from a completely flat to a very curved shield which has the same shape of curvature at its top and bottom and covers the entire face. The influence of the shield is analyzed with two types of experiments – one using dummy head with integrated artificial voice device, and the other using real speakers (female and male actors). It has been shown that usage of protective shields results in a relative increase in the speech signal level, in the frequency range of around 1000 Hz, compared to the situation when protective shields are not used. The relative increase in speech signal levels for large-curvature shields can be up to 8 dB. The possible causes of this phenomenon have been analyzed and examined.

This paper examines speech privacy in both residential and commercial spaces. The ASTM E2638 standard defines the Speech Privacy Class (SPC) parameter, which measures speech privacy based on the signal-to-noise ratio at the listener’s position. This paper proposes estimating the SPC value using relevant ISO parameters commonly used in European practice: the apparent sound reduction index in dB (defined by ISO 16283-1, 2 standards) and the equivalent ambient noise level in dBA (defined by the ISO 1996-1 standard). The estimated value of the SPC parameter in this paper is referred to as the Speech Privacy Index (SPI). A diverse range of situations, i.e., rooms, was analyzed in the field. These rooms varied in terms of purpose, organization, dimensions, furnishings, isolation from other spaces, and internal and external environments. The results of the experiments demonstrate a strong correlation between the SPC value estimated according to ISO parameters (the proposed method) and the SPC as defined in the ASTM E standard. This indicates that the proposed method can provide an indicator of the state of speech privacy in buildings. The significance of the proposed calculation method (i.e., the STI parameter) lies in its ability to be applied at the building design stage, as well as after its completion, during routine testing.

In urban environments, people's exposure to harmful ambient conditions and noise represents a particular challenge in the modern world. Global climate change and increasing population density, along with the increasing number of vehicles in urban areas, are constantly exacerbating this problem. The idea of this study is to assess the effects of temperature risks and noise pollution in two microlocations. An analysis of the ambient conditions and noise in the urban environment was conducted at two locations in Belgrade, which differed in configuration. Simultaneous measurements of temperature (Ta and Tg), humidity, wind speed, and equivalent noise level were taken during a hot summer day (maximum temperature over 30?C). It was shown that the noise level exceeds the prescribed noise level values for the analyzed acoustic zone. The noise level values differ for the two locations due to the different traffic densities in the environment and different urban characteristics. This study showed that the concept of green space, but also of built-up type in urban planning could has importance impact in regulating thermal and noise conditions and obtained improved urban environments.